U.S. patent application number 16/445500 was filed with the patent office on 2020-12-24 for integrated circuits for generating input/output latency performance metrics using real-time clock (rtc) read measurement module.
The applicant listed for this patent is Intel Corporation. Invention is credited to Garrett Matthias Drown, Patrick Lu.
Application Number | 20200401538 16/445500 |
Document ID | / |
Family ID | 1000005261159 |
Filed Date | 2020-12-24 |
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United States Patent
Application |
20200401538 |
Kind Code |
A1 |
Drown; Garrett Matthias ; et
al. |
December 24, 2020 |
INTEGRATED CIRCUITS FOR GENERATING INPUT/OUTPUT LATENCY PERFORMANCE
METRICS USING REAL-TIME CLOCK (RTC) READ MEASUREMENT MODULE
Abstract
An integrated circuit includes technology for generating
input/output (I/O) latency metrics. The integrated circuit includes
a real-time clock (RTC), a read measurement register, and a read
latency measurement module. The read latency measurement module
includes control logic to perform operations comprising (a) in
response to receipt of read responses that complete read requests
associated with an I/O device, automatically calculating read
latencies for the completed read requests, based at least in part
on time measurements from the RTC for initiation and completion of
the read requests; (b) automatically calculating an average read
latency for the completed read requests, based at least in part on
the calculated read latencies for the completed read requests; and
(c) automatically updating the read measurement register to record
the average read latency for the completed read requests. Other
embodiments are described and claimed.
Inventors: |
Drown; Garrett Matthias;
(Chandler, AZ) ; Lu; Patrick; (Sammamish,
WA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Intel Corporation |
Santa Clara |
CA |
US |
|
|
Family ID: |
1000005261159 |
Appl. No.: |
16/445500 |
Filed: |
June 19, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G06F 9/30098 20130101;
G06F 2213/0026 20130101; G06F 13/126 20130101; G06F 13/20
20130101 |
International
Class: |
G06F 13/20 20060101
G06F013/20; G06F 13/12 20060101 G06F013/12; G06F 9/30 20060101
G06F009/30 |
Claims
1. An integrated circuit with technology for generating
input/output latency metrics, the integrated circuit comprising: a
real-time clock (RTC); a read measurement register; and a read
latency measurement module, wherein the read latency measurement
module comprises control logic to perform operations comprising: in
response to receipt of read responses that complete read requests
associated with an input/output (I/O) device, automatically
calculating read latency for the completed read requests, based at
least in part on time measurements from the RTC for initiation and
completion of the completed read requests; automatically
calculating an average read latency for the completed read
requests, based at least in part on the calculated read latencies
for the completed read requests; and automatically updating the
read measurement register to record the average read latency for
the completed read requests.
2. An integrated circuit according to claim 1, wherein the read
latency monitor further comprises control logic to perform
operations comprising: automatically determining a minimum read
latency for the completed read requests; automatically determining
a maximum read latency for the completed read requests; and
automatically updating the read measurement register to record the
minimum read latency and the maximum read latency.
3. An integrated circuit according to claim 1, further comprising:
an I/O manager to manage the read requests, wherein the I/O manager
comprises the RTC, the read measurement register, and the read
latency measurement module.
4. An integrated circuit according to claim 3, wherein: the I/O
manager is configured to send a device read request to the I/O
device in response to receiving a host read request from a
processing core; and the completed read requests comprise device
read requests.
5. An integrated circuit according to claim 4, wherein the I/O
manager complies with revision 3.0 of a Peripheral Component
Interconnect Express (PCIe) base specification.
6. An integrated circuit according to claim 5, wherein the I/O
manager comprises a PCIe root complex.
7. A central processing unit (CPU) comprising: the integrated
circuit according to claim 3; and a processing core in the
integrated circuit to send host read requests to the I/O
manager.
8. A data processing system comprising: the CPU according to claim
7; and the I/O device.
9. A data processing system according to claim 8, wherein: the I/O
manager comprises a root port connected to multiple I/O devices;
and the operation of automatically calculating average read latency
for the completed read requests comprises of automatically
calculating average read latency for completed read requests
involving any of the I/O devices connected to the root port.
10. A data processing system with technology for generating
input/output latency metrics, the data processing system
comprising: an input/output (I/O) manager; an I/O device responsive
to the I/O manager; a central processing unit (CPU) to communicate
with the I/O device via the I/O manager; a real-time clock (RTC) in
the I/O manager; a read measurement register in the I/O manager;
and a read latency measurement module in the I/O manager, wherein
the read latency measurement module comprises control logic to
perform operations comprising: in response to receipt of read
responses that complete read requests associated with the I/O
device, automatically calculating read latency for the completed
read requests, based at least in part on time measurements from the
RTC for initiation and completion of the completed read requests;
automatically calculating an average read latency for the completed
read requests, based at least in part on the calculated read
latencies for the completed read requests; and automatically
updating the read measurement register to record the average read
latency for the completed read requests.
11. A data processing system according to claim 10, wherein the
read latency monitor further comprises control logic to perform
operations comprising: automatically determining a minimum read
latency for the completed read requests; automatically determining
a maximum read latency for the completed read requests; and
automatically updating the read measurement register to record the
minimum read latency and the maximum read latency.
12. A data processing system according to claim 10, wherein: the
I/O manager is configured to send a device read request to the I/O
device in response to receiving a host read request from a
processing core; and the completed read requests comprise device
read requests.
13. A data processing system according to claim 12, wherein the I/O
manager complies with revision 3.0 of a Peripheral Component
Interconnect Express (PCIe) base specification.
14. A data processing system according to claim 13, wherein the I/O
manager comprises a PCIe root complex.
15. A data processing system according to claim 10, wherein: the
I/O manager comprises a root port connected to multiple I/O
devices; and the operation of automatically calculating average
read latency for the completed read requests comprises of
automatically calculating average read latency for completed read
requests involving any of the I/O devices connected to the root
port.
16. A method for generating input/output latency metrics, the
method comprising: at a read latency measurement module in an
input/output (I/O) manager of a data processing system, in response
to receipt of read responses that complete read requests associated
with an I/O device, automatically calculating read latencies for
the completed read requests, based at least in part on time
measurements from a real-time clock (RTC) for initiation and
completion of the completed read requests; at the read latency
measurement module, automatically calculating an average read
latency for the completed read requests, based at least in part on
the calculated read latencies for the completed read requests; and
automatically updating a read measurement register in the I/O
manager to record the average read latency for the completed read
requests.
17. A method according to claim 16, further comprising: at the read
latency measurement module, automatically determining a minimum
read latency for the completed read requests and automatically
determining a maximum read latency for the completed read requests;
and automatically updating the read measurement register to record
the minimum read latency and the maximum read latency.
18. A method according to claim 16, further comprising: at the I/O
manager, receiving a host read request from a processing core of
the data processing system; and automatically sending a device read
request from the I/O manager to the I/O device, in response to
receiving the host read request from the processing core; and
wherein the completed read requests comprise device read
requests.
19. A method according to claim 18, further comprising: at the I/O
manager, managing read requests as a Peripheral Component
Interconnect Express (PCIe) root complex, in accordance with
revision 3.0 of a PCIe base specification.
20. A method according to claim 16, further comprising: receiving
the read responses via a root port of the I/O manager that is
connected to multiple I/O devices; and wherein the operation of
automatically calculating average read latency for the completed
read requests comprises of automatically calculating average read
latency for completed read requests involving any of the I/O
devices connected to the root port.
21. An integrated circuit with technology for generating
input/output latency metrics, the integrated circuit comprising: an
input/output (I/O) manager to manage read requests, wherein the I/O
manager complies with revision 3.0 of a Peripheral Component
Interconnect Express (PCIe) base specification; a real-time clock
(RTC) in the I/O manager; a read measurement register in the I/O
manager; and a read latency measurement module in the I/O manager,
wherein the read latency measurement module comprises control logic
to perform operations comprising: in response to receipt of read
responses that complete read requests associated with an I/O
device, automatically calculating read latency for the completed
read requests, based at least in part on time measurements from the
RTC for initiation and completion of the completed read requests;
automatically calculating an average read latency for the completed
read requests, based at least in part on the calculated read
latencies for the completed read requests; and automatically
updating the read measurement register to record the average read
latency for the completed read requests.
22. An integrated circuit according to claim 21, wherein the read
latency monitor further comprises control logic to perform
operations comprising: automatically determining a minimum read
latency for the completed read requests; automatically determining
a maximum read latency for the completed read requests; and
automatically updating the read measurement register to record the
minimum read latency and the maximum read latency.
23. An integrated circuit according to claim 21, wherein the I/O
manager comprises a PCIe root complex.
Description
TECHNICAL FIELD
[0001] The present disclosure pertains in general to data
processing systems and in particular to technology for generating
metrics pertaining to the performance of input/output devices.
BACKGROUND
[0002] The overall performance of a data processing system may be
significantly affected by the efficiency of communications between
one or more processor cores and one or more input/output (I/O)
devices. For instance, high I/O response time may cause wasted core
cycles, and wasted core cycles may cause sub-optimal performance.
In addition, a conventional data processing system lacks features
for efficiently generating performance metrics for communications
between cores and I/O devices.
[0003] As described in greater detail below, the present disclosure
introduces technology for generating metrics pertaining to the
performance of I/O devices.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] Features and advantages of the present invention will become
apparent from the appended claims, the following detailed
description of one or more example embodiments, and the
corresponding figures, in which:
[0005] FIG. 1 is a block diagram depicting an example embodiment of
a data processing system with technology for generating I/O latency
metrics.
[0006] FIG. 2 is a block diagram depicting the read latency
measurement module of FIG. 1 in greater detail.
[0007] FIGS. 3A and 3B present a flowchart of an example embodiment
of a process for generating I/O latency metrics.
[0008] FIG. 4 is a block diagram illustrating both an exemplary
in-order pipeline and an exemplary register renaming, out-of-order
issue/execution pipeline according to embodiments of the
invention.
[0009] FIG. 5 is a block diagram illustrating both an exemplary
embodiment of an in-order architecture core and an exemplary
register renaming, out-of-order issue/execution architecture core
to be included in a processor according to embodiments of the
invention.
[0010] FIGS. 6 and 7 are block diagrams of a more specific
exemplary in-order core architecture, which core would be one of
several logic blocks (including other cores of the same type and/or
different types) in a chip.
[0011] FIG. 8 is a block diagram of a processor that may have more
than one core, may have an integrated memory controller, and may
have integrated graphics according to embodiments of the
invention.
[0012] FIG. 9 is a block diagram of a system according to
embodiments of the invention.
[0013] FIGS. 10 and 11 are block diagrams of more specific
exemplary systems according to embodiments of the invention.
[0014] FIG. 12 is a block diagram of a system on a chip according
to embodiments of the invention.
DETAILED DESCRIPTION
[0015] If a data processing system could measure certain aspects of
I/O device performance, those measurements could then be used to
tune, configure, and/or redesign certain aspects of the data
processing system in such a way as to improve the overall
performance of the data processing system. In particular, it could
be useful to generate metrics such as minimum response time,
maximum response time, and average response time for one, some, or
all of the I/O devices in the data processing system. For purposes
of this disclosure, such metrics may be referred to in general as
I/O performance metrics and more specifically as I/O response time
metrics or I/O latency metrics.
[0016] A conventional data processing system lacks features for
accurately and efficiently generating I/O latency metrics.
Moreover, it may be difficult or impossible to develop software
that would be capable of efficiently generating accurate I/O
latency metrics in a conventional data processing system.
[0017] By contrast, a data processing system according to the
present disclosure includes technology for generating I/O latency
metrics. Moreover, such technology may be very accurate and very
efficient, and it may generate such metrics in real time.
Additionally, this technology may be implemented without adding
extensive circuitry to the design of a conventional integrated
circuit, and this technology may enable hardware and software
designers to optimize system performance.
[0018] FIG. 1 is a block diagram depicting an example embodiment of
a data processing system 10 with technology for generating I/O
latency metrics. Data processing system 10 includes a processor 12
in communication with random access memory (RAM) 12. In the
embodiment of FIG. 1, processor 12 is a central processing unit
(CPU) with two processing cores 20A and 20B. However, in
alternative embodiments, a data processing system may include one
or more CPUs, and each CPU may include one or more cores.
[0019] In the embodiment of FIG. 1, core 20A includes various
processing resources, such as at least one arithmetic logic unit
(ALU) 22, a set of general purpose registers (GPRs) 24, etc. Core
20B may include the same or similar types of processing
resources.
[0020] Data processing system 10 also includes various I/O devices,
such as non-volatile storage (NVS) 16, a network interface
controller (NIC) 18, and a graphics adapter 17. NVS 16 may be a
Non-volatile Memory Express (NVMe) drive, for instance. Cores 20A
and 20B may communicate with those I/O devices via an I/O manager
30. For purposes of this disclosure, any device that a processing
core communicates with via an I/O manager may be referred to as an
I/O device. Accordingly, I/O devices may include field programmable
gate arrays (FPGAs), Peripheral Component Interconnect Express
(PCIe) solid-state drives (SSDs), Serial AT Attachment (SATA) disks
connected to a PCIe controller, accelerators, etc. Also, in an
alternative embodiment, one or more cores may connect to RAM via an
I/O manager. Nevertheless, RAM is not considered to be an I/O
device.
[0021] In the embodiment of FIG. 1, I/O manager 30 is an integrated
I/O controller that resides in the same integrated circuit as cores
20A and 20B. However, in other embodiments, data processing systems
may use I/O managers that reside in separate integrated circuits
from the processing cores. For example, the cores and the I/O
manager may reside in separate chips in a multi-chip package, or
the I/O manager may reside in a separate package from the cores.
Furthermore, a data processing system may include multiple I/O
managers. For instance, a data processing system may include a CPU
that contains multiple I/O managers, multiple CPUs that each
contain one I/O manager, etc.
[0022] As indicated above, a core may communicate with an I/O
device via an I/O manager. In particular, when a core reads from an
I/O device via an I/O manager, the I/O manager handles that read
transaction by (a) sending a read request to the I/O device on
behalf of the core, (b) waiting for a corresponding response (or
multiple responses) from the I/O device, and then (c) communicating
the result back to the core. If the read was successful, the result
will include the data that was read from the I/O device. If the
read was not successful, the result may include an error message
(or no result at all). Thus, read transactions involve request
messages that are separate in time from the corresponding response
messages. For instance, the read request that the I/O manager sends
to the I/O device is separate in time from the corresponding
response that the I/O device sends to the I/O manager.
Consequently, a read transaction may be referred as a split
transaction.
[0023] For purposes of this disclosure, communications between a
core and an I/O manager may be referred to as host communications,
and communications between an I/O manager and an I/O device may be
referred to device communications. In particular, for a read
transaction, the request from the core to the I/O manager may be
referred to as a host read request, and the subsequent message
(with the result) from the I/O manager to the core may be referred
to as a host read response. Similarly, the message from the I/O
manager to the I/O device may be referred to as a device read
request, and the subsequent message from the I/O device to the I/O
manager may be referred to as a device read response.
[0024] In the hypothetical embodiment of FIG. 1, I/O manager 30
complies with revision 3.0 of the PCIe base specification (the
"PCIe Specification"). I/O manager 30 may also comply with
subsequent versions of the PCIe Specification (e.g., revision 4.x,
5.x, etc.). In particular, I/O manager 30 may serve as a PCIe root
complex, containing a host bridge and a multiple root ports.
However, in other embodiments, data processing systems may include
I/O managers which comply with other specifications and/or with
proprietary I/O device management protocols.
[0025] In the embodiment of FIG. 1, NVS 16 includes various
software components, including an operating system (OS) 52, a user
application 54, and performance monitoring code 50. Data processing
system 10 may copy such software components into RAM 14 for
execution. As described in greater detail below, I/O manager 30 may
generate metrics pertaining to the performance of the I/O devices
in data processing system 10, and one or more of those software
components may use those performance metrics to improve or optimize
system performance.
[0026] In the embodiment of FIG. 1, I/O manager 30 includes a host
bridge 32 to enable communications between I/O manager 30 and cores
20A and 20B. I/O manager 30 also include a real-time clock (RTC)
34. I/O manager 30 also include multiple root ports 36A, 36B, and
36C to enable communications between I/O manager 30 and the I/O
devices. In particular, I/O manager 30 communicates with graphics
adapter 17 via root port 36A, with NIC 18 via root port 36B, and
with NVS 16 via root port 36C. However, in one or more alternative
embodiments, an I/O manager may communicate with more than one I/O
device via a single root port. For instance, a root port may
connect to a switch, the switch may connect to two or more I/O
devices, and the I/O manager may communicate with those I/O devices
via that root port and that switch.
[0027] In the embodiment of FIG. 1, the components within I/O
manager 30 for generating performance metrics include I/O
measurement modules (IOMMs) 40A, 40B, and 40C. Each IOMM generates
metrics for a different root port, with IOMM 40A generating metrics
for communications which use root port 36A, IOMM 40B generating
metrics for communications which use root port 36B, and IOMM 40C
generating metrics for communications which use root port 36C.
Accordingly, when a root port is connected to only one I/O device,
the corresponding IOMM generates metrics for that particular I/O
device. And when a root port is connected to multiple I/O devices,
the corresponding IOMM generates aggregate metrics for those
multiple I/O devices.
[0028] As illustrated within IOMM 40A, the components within an
IOMM for generating performance metrics include a read latency
measurement module 42, a read measurement register 46, and
configuration settings 48. Although not illustrated in FIG. 1,
IOMMs 40B and 40C may also include such components. In an
alternative embodiment, each IOMM may include its own RTC for
determining start times and completion times.
[0029] In the embodiment of FIG. 1, read latency measurement module
42 includes a pending read table 43. Also, read measurement
register 46 includes a read metrics table 47. As described in
greater detail below, read latency measurement module 42 (a)
monitors device read requests and device read responses which
traverse root port 36A, (b) generates I/O device performance
metrics based on those requests and responses, and (c) saves those
metrics to read metrics table 47 in read measurement register 46.
In the embodiment of FIG. 1, those metrics include average read
latency, maximum read latency, and minimum read latency, for read
requests involving root port 36A. Other components of data
processing system 10 (e.g., performance monitoring code 50) may
then use those metrics to improve or optimize overall system
performance.
[0030] Also, FIG. 1 depicts an IOMM with a single read measurement
register. However, in an alternative embodiment, each IOMM may use
multiple registers to store measurements such as average, minimum,
and maximum read latency. For instance, an IOMM may use a "running
average register" to store the average read latency, a "minimum
latency register" to store the minimum read latency, and a "maximum
latency register" to store the maximum read latency.
[0031] FIG. 2 is a block diagram depicting read latency measurement
module 42 in greater detail. As indicated above, read latency
measurement module 42 includes pending read table 43. Read latency
measurement module 42 may use pending read table 43 to provide for
time-out processing for read requests. In particular, for each
device read request that IOMM 40A transmits via root port 36A, read
latency measurement module 42 may store a request identifier (ID)
for that read request and a start time for that read request in
pending read table 43. And read latency measurement module 42 may
determine that start time based on RTC 34. IOMM 40A may be
configured with a predetermined timeout limit. And if IOMM 40A does
not see a response for a read request before that timeout limit is
reached, IOMM 40A may conclude that the read request has timed out
or expired. Accordingly, IOMM 40A may perform timeout processing
for that read request. For instance, IOMM 40A may send a host
response to the core associated with the expired request, and that
host response may indicate that the read request timed out or
expired.
[0032] Furthermore, read latency measurement module 42
automatically computes performance metrics for reads that complete
successfully. In particular, whenever IOMM 40A receives a device
read response that completes a device read request, read latency
measurement module 42 uses RTC 34 to determine the completion time
of that request. Read latency measurement module 42 may then add
that completion time to pending read table 43. In addition or
alternatively, read latency measurement module 42 may save the
completion time in a different place, such as a work register. In
addition, read latency measurement module 42 determines the total
elapsed time for completion of the read request, based on the start
time and completion time. That total elapsed time may also be
referred to as the total latency or the calculated latency. Once
the total latency has been calculated, the associated entry in
pending read table 43 may be removed or reused. Thus, read latency
measurement module 42 calculates latency for completed device read
requests based on time measurements from RTC 34 for initiation and
completion of those requests.
[0033] In addition, as described in greater detail below, read
latency measurement module 42 uses the calculated latency for each
completed request to generate more general performance metrics for
root port 36A. Read latency measurement module 42 may then store
those metrics in read metrics table 47. For instance, read latency
measurement module 42 may calculate an average read latency, a
maximum read latency, and a minimum read latency, for all completed
device read requests that have traversed root port 36A. And since
root port 36A is connected only to graphics adapter 17, those
performance metrics apply as well to graphics adapter 17.
[0034] FIGS. 3A and 3B present a flowchart of an example embodiment
of a process for generating I/O latency metrics. That process is
described with regard to the embodiment of FIG. 1. In particular,
for purposes of illustration, the process is described with regard
to IOMM 40A generating performance metrics for graphics adapter 17,
which is accessed via root port 36A. However, each IOMM in an I/O
manager may use the same process to generate performance metrics
for the I/O device (or devices) accessed via the root port
associated with that IOMM.
[0035] The process of FIG. 3A starts at block 110 with IOMM 40A
determining whether I/O manager 30 has just sent a device read
request to an I/O device via root port 36A. If such a read request
was just sent, IOMM 40A determines the start time for that read
request, based on RTC 34, as shown at block 112. And as shown at
block 114, IOMM 40A adds an entry to pending read table 43 to
record the start time for that read request, along with a tag or
request ID for that read request. Thus, IOMM 40A tracks the start
time for each device read request that traverses root port 36A.
[0036] After updating pending read table 43, or if no read request
was detected at block 110, IOMM 40A may then determine whether I/O
manager 30 has just received a device read response via root port
36A, as shown at block 120. If no such response was received, IOMM
40A may determine whether any device read requests have timed out,
as shown at block 130. For instance, I/O manager 30 may be
configured with a predetermined timeout threshold, and IOMM 40A may
use pending read table 43 and RTC 34 to determine whether any of
the pending device read requests have been pending for longer than
the timeout threshold. As shown at block 132, if a device read
request has timed out, IOMM 40A may perform timeout processing for
that request. Timeout processing may include any suitable
operations, such as retrying the read request a predetermined
number of times, sending an error result to report the timeout to
the core associated with the read request, removing the entry from
pending read table 43, etc. The process may then return to block
110, with IOMM 40A repeating the operations described above and
below, as applicable.
[0037] Referring again to block 120, in response to I/O manager 30
receiving a device read response via root port 36A, IOMM 40A may
determine whether that response completes a device read request, as
shown at block 140. For instance, if the request required only a
single response, IOMM 40A may consider the request completed when
that response is received. Or if the request required multiple
responses, IOMM 40A may consider the request completed when the
last required response is received. In one embodiment, each device
read request and each device read response includes a tag or
request ID, and IOMM 40A uses that request ID to match each
response to the corresponding request.
[0038] If IOMM 40A determines that a received device read response
does not complete a device read request, the process may return to
block 110, with IOMM 40A repeating the operations described above
and below, as applicable. However, if a received device read
response does complete a device read request, the process may pass
through page connector B to FIG. 3B, which illustrates various
operations performed by IOMM 40A in response to a positive
determination at block 140.
[0039] In particular, as shown at block 152, read latency
measurement module 42 in IOMM 40A uses RTC 34 to determine the
completion time for the device read request. Also, read latency
measurement module 42 uses that completion time and the start time
from pending read table 43 to compute the total latency for the
device read request, as shown at block 154. Also, as shown at block
156, IOMM 40A removes the entry for the completed device read
request from pending read table 43.
[0040] Read latency measurement module 42 also uses the calculated
latency for the completed device read request to update the I/O
latency metrics pertaining to root port 36A and graphics adapter 17
in read metrics table 47. In particular, as shown at block 158,
read latency measurement module 42 calculates a running average for
the read latency for root port 36A and graphics adapter 17, based
on the calculated latency for the completed device read request.
And as shown at block 159, read latency measurement module 42 uses
that result to update the average read latency in read metrics
table 47.
[0041] To reduce the rate of overflows, read latency measurement
module 42 may compute the average read latency using a formula that
does not require a sum of all latencies to be maintained. For
instance, in one embodiment, read latency measurement module 42
uses a formula such as the following:
new-average=old-average+(new-latency-old-average)/count
where "count" indicates how many completed device read requests
have been used to generate the "new-average" latency value. With
such a formula, the most probable source of overflow would only
occur when the value of "count" exceeds 2.sup.64 (assuming a 64-bit
counter). With 64-byte reads at conventional I/O speeds, that might
take over 1000 years.
[0042] Also, as shown at block 160, read latency measurement module
42 determines whether the computed latency is greater than the
maximum latency measured so far. If it is, read latency measurement
module 42 updates the maximum latency value in read metrics table
47, as shown at block 162. Also, as shown at block 170, read
latency measurement module 42 determines whether the computed
latency is less than the minimum latency measured so far. If it is,
read latency measurement module 42 updates the minimum latency
value in read metrics table 47, as shown at block 172.
[0043] As described above, in one embodiment, read latency
measurement module 42 computes the latency for a device read
request based on the time of the last response that was required to
complete the request. Accordingly, the latency may be referred to
as last completion latency. However, in another embodiment or
scenario, the read latency measurement module may compute the
latency for a device read request based on the time of the first
response which corresponds to that read request. In that case, the
latency may be referred to as first completion latency. In another
embodiment or scenario, the read latency measurement module may
compute both last completion latency and first completion latency,
and the read latency measurement module may generate and save two
sets of general I/O latency metrics (e.g., average, minimum, and
maximum latency), with one set based on last completion latency and
the other based on first completion latency.
[0044] Referring again to FIG. 3B, after read latency measurement
module 42 generates and saves the general performance metrics, the
process may then return to block 110 of FIG. 3A via page connector
A, with IOMM 40A repeating the operations described above and
below, as applicable.
[0045] Thus, as described above, IOMM 40A generates and saves I/O
latency metrics for communications between the cores of processor
18 and graphics adapter 17. And the other IOMMs generate and save
I/O latency metrics for communications between the cores of
processor 18 and the I/O devices connected to the other root ports
of I/O manager 30. As indicated above, those metrics provide
information about I/O device response time. In particular, those
metrics indicate the average, minimum, and maximum latency for
completed device read requests associated with each different root
port that is managed by I/O manager 30.
[0046] In one embodiment, read latency measurement module 42 is
implemented using control logic which does not require much space
or "real estate" within I/O manager 30. In addition, that control
logic does not impact signal integrity. Also, I/O manager 30
enables components such as performance monitoring code 50, OS 52,
and/or user application 54 to obtain metrics concerning I/O
response time without using external hardware. Moreover, I/O
manager 30 enables users to run extended tests and capture very
accurate minimum, maximum, and average latency values without
capturing an enormous amount of data. For instance, a test may be
run (and data collected) for minutes, hours, days, weeks, or even
longer.
[0047] As indicated above, a data processing system may include
various software components which use the performance metrics from
a read measurement register to improve or optimize system
performance. For purposes of this disclosure, a software or
hardware component which (a) obtains performance metrics from a
read measurement register and (b) uses those metrics to facilitate
performance improvements may be referred to as a metrics consumer.
Metrics consumers may obtain such performance metrics directly from
a read measurement register, or indirectly, via one or more
intermediate components. As described in greater detail below,
metrics consumers may be applications, OSs, drivers, or any other
component which uses I/O latency metrics like those described
herein.
[0048] In the embodiment of FIG. 1, each IOMM includes
configuration settings 48 which may be read and modified by a
metrics consumer. Configuration settings 48 may reside in a
special-purpose register (SPR) or a model-specific register (MSR),
for example. A metrics consumer may update configuration settings
48 to configure components such as IOMMs and read latency
measurement modules. For instance, a metrics consumer may write a
particular value to configuration settings 48 to cause IOMM 40A to
reset the latency values in read metrics table 47.
[0049] The technology described herein may be used in many
different embodiments of data processing systems and many different
scenarios to realize or facilitate improved performance, relative
to conventional data processing systems. For instance, metrics
consumers may utilize the performance metrics to dynamically
realize performance improvements. In addition or alternatively,
metrics consumers may use the metrics to facilitate debugging,
benchmarking, and other types of operations.
[0050] With regard to dynamically realizing performance
improvements, in one embodiment, a user application may include
logic for making determinations concerning I/O device performance
and for taking action based on those determinations. For instance,
the application may send more work to I/O devices with low latency.
The application may read the average, maximum, and minimum read
latency values directly from the read measurement registers of the
various IOMMs, or the application may obtain the latency metrics
from an OS or other intermediate source.
[0051] In another embodiment, an OS may read the average, maximum,
and minimum read latency values directly from the read measurement
registers of the various IOMMs, and the OS may make determinations
concerning system performance and take corresponding actions (e.g.,
reporting unusual conditions) based on those determinations. For
instance, the OS may recognize and measure latency spikes, the OS
may then correlate those spikes with events in the system, and the
OS may then log or report its findings, thereby providing valuable
information for debugging and root causing issues and/or developing
performance optimizations.
[0052] In another embodiment, performance monitoring code that runs
in a data processing system in a test or development environment
may analyze the I/O latency metrics and generate reports based on
that analysis. The analysis and reports may involve events such as
latency spikes and corresponding events in the system, for
instance. However, the generation of I/O latency metrics may be
disabled in a production environment, or access to those metrics
may be protected or disabled in the production environment.
[0053] In another embodiment, the I/O manager may be considered to
be a performance monitoring ("PMON") component, it may reside in an
uncore portion of a CPU along with other PMON components or units,
and those PMON units may be governed by a global control. Metrics
consumers may use techniques similar to those described in the
Intel.RTM. Xeon.RTM. Processor Scalable Memory Family Uncore
Performance Monitoring Reference Manual from July of 2017 (a) to
access and configure components such as IOMMs, (b) to read latency
measurement modules, and (c) to generate reports based on the
metrics collected from those components.
[0054] In one embodiment, the read measurement register may be an
SPR or MSR that metrics consumers can read and/or update. In
another embodiment, the read measurement register may be a
Peripheral Component Interconnect (PCI) register. In another
embodiment, metrics consumers may obtain the performance metrics
from the read measurement register via a PMON framework.
Additional Embodiments
[0055] FIG. 4 is a block diagram illustrating both an exemplary
in-order pipeline and an exemplary register renaming, out-of-order
issue/execution pipeline according to embodiments of the invention.
FIG. 5 is a block diagram illustrating both an exemplary in-order
architecture core and an exemplary register renaming, out-of-order
issue/execution architecture core to be included in a processor
according to embodiments of the invention. The solid lined boxes in
FIGS. 4 and 5 illustrate the in-order pipeline and in-order core,
while the optional addition of the dashed lined boxes illustrates
the register renaming, out-of-order issue/execution pipeline and
core. Given that the in-order aspect is a subset of the
out-of-order aspect, the out-of-order aspect will be described.
[0056] In FIG. 4, a processor pipeline 900 includes a fetch stage
902, a length decode stage 904, a decode stage 906, an allocation
stage 908, a renaming stage 910, a scheduling (also known as a
dispatch or issue) stage 912, a register read/memory read stage
914, an execute stage 916, a write back/memory write stage 918, an
exception handling stage 922, and a commit stage 924.
[0057] FIG. 5 shows processor core 990 including a front end unit
930 coupled to an execution engine unit 950, and both are coupled
to a memory unit 970. The core 990 may be a reduced instruction set
computing (RISC) core, a complex instruction set computing (CISC)
core, a very long instruction word (VLIW) core, or a hybrid or
alternative core type. As yet another option, the core 990 may be a
special-purpose core, such as, for example, a network or
communication core, a compression engine, a coprocessor core, a
general-purpose graphics processing unit (GPGPU), a graphics core,
or the like.
[0058] The front end unit 930 includes a branch prediction unit 932
coupled to an instruction cache unit 934, which is coupled to an
instruction translation lookaside buffer (TLB) 936, which is
coupled to an instruction fetch unit 938, which is coupled to a
decode unit 940. The decode unit 940 (or decoder) may decode
instructions, and generate as an output one or more
micro-operations, micro-code entry points, microinstructions, other
instructions, or other control signals, which are decoded from, or
which otherwise reflect, or are derived from, the original
instructions. The decode unit 940 may be implemented using various
different mechanisms. Examples of suitable mechanisms include, but
are not limited to, look-up tables, hardware implementations,
programmable logic arrays (PLAs), microcode read only memories
(ROMs), etc. In one embodiment, the core 990 includes a microcode
ROM or other medium that stores microcode for certain
macroinstructions (e.g., in decode unit 940 or otherwise within the
front end unit 930). The decode unit 940 is coupled to a
rename/allocator unit 952 in the execution engine unit 950.
[0059] The execution engine unit 950 includes the rename/allocator
unit 952 coupled to a retirement unit 954 and a set of one or more
scheduler unit(s) 956. The scheduler unit(s) 956 represents any
number of different schedulers, including reservations stations,
central instruction window, etc. The scheduler unit(s) 956 is
coupled to the physical register file(s) unit(s) 958. Each of the
physical register file(s) units 958 represents one or more physical
register files, different ones of which store one or more different
data types, such as scalar integer, scalar floating point, packed
integer, packed floating point, vector integer, vector floating
point, status (e.g., an instruction pointer that is the address of
the next instruction to be executed), etc. In one embodiment, the
physical register file(s) unit 958 comprises a vector registers
unit, a write mask registers unit, and a scalar registers unit.
These register units may provide architectural vector registers,
vector mask registers, and general purpose registers. The physical
register file(s) unit(s) 958 is overlapped by the retirement unit
954 to illustrate various ways in which register renaming and
out-of-order execution may be implemented (e.g., using a reorder
buffer(s) and a retirement register file(s); using a future
file(s), a history buffer(s), and a retirement register file(s);
using a register maps and a pool of registers; etc.). The
retirement unit 954 and the physical register file(s) unit(s) 958
are coupled to the execution cluster(s) 960. The execution
cluster(s) 960 includes a set of one or more execution units 962
and a set of one or more memory access units 964.
[0060] The execution units 962 may perform various operations
(e.g., shifts, addition, subtraction, multiplication) and on
various types of data (e.g., scalar floating point, packed integer,
packed floating point, vector integer, vector floating point).
While some embodiments may include a number of execution units
dedicated to specific functions or sets of functions, other
embodiments may include only one execution unit or multiple
execution units that all perform all functions. The scheduler
unit(s) 956, physical register file(s) unit(s) 958, and execution
cluster(s) 960 are shown as being possibly plural because certain
embodiments create separate pipelines for certain types of
data/operations (e.g., a scalar integer pipeline, a scalar floating
point/packed integer/packed floating point/vector integer/vector
floating point pipeline, and/or a memory access pipeline that each
have their own scheduler unit, physical register file(s) unit,
and/or execution cluster--and in the case of a separate memory
access pipeline, certain embodiments are implemented in which only
the execution cluster of this pipeline has the memory access
unit(s) 964). It should also be understood that where separate
pipelines are used, one or more of these pipelines may be
out-of-order issue/execution and the rest in-order.
[0061] The set of memory access units 964 is coupled to the memory
unit 970, which includes a data TLB unit 972 coupled to a data
cache unit 974 coupled to a level 2 (L2) cache unit 976. In one
exemplary embodiment, the memory access units 964 may include a
load unit, a store address unit, and a store data unit, each of
which is coupled to the data TLB unit 972 in the memory unit 970.
The instruction cache unit 934 is further coupled to a level 2 (L2)
cache unit 976 in the memory unit 970. The L2 cache unit 976 is
coupled to one or more other levels of cache and eventually to a
main memory.
[0062] By way of example, the exemplary register renaming,
out-of-order issue/execution core architecture may implement the
pipeline 900 as follows: 1) the instruction fetch 938 performs the
fetch and length decoding stages 902 and 904; 2) the decode unit
940 performs the decode stage 906; 3) the rename/allocator unit 952
performs the allocation stage 908 and renaming stage 910; 4) the
scheduler unit(s) 956 performs the schedule stage 912; 5) the
physical register file(s) unit(s) 958 and the memory unit 970
perform the register read/memory read stage 914; the execution
cluster 960 performs the execute stage 916; 6) the memory unit 970
and the physical register file(s) unit(s) 958 perform the write
back/memory write stage 918; 7) various units may be involved in
the exception handling stage 922; and 8) the retirement unit 954
and the physical register file(s) unit(s) 958 perform the commit
stage 924.
[0063] The core 990 may support one or more instructions sets
(e.g., the x86 instruction set (with some extensions that have been
added with newer versions); the MIPS instruction set of MIPS
Technologies of Sunnyvale, Calif.; the ARM instruction set (with
optional additional extensions such as NEON) of ARM Holdings of
Sunnyvale, Calif.), including the instruction(s) described herein.
In one embodiment, the core 990 includes logic to support a packed
data instruction set extension (e.g., AVX1, AVX2), thereby allowing
the operations used by many multimedia applications to be performed
using packed data.
[0064] It should be understood that the core may support
multithreading (executing two or more parallel sets of operations
or threads), and may do so in a variety of ways including time
sliced multithreading, simultaneous multithreading (where a single
physical core provides a logical core for each of the threads that
physical core is simultaneously multithreading), or a combination
thereof (e.g., time sliced fetching and decoding and simultaneous
multithreading thereafter such as in the Intel.RTM. Hyperthreading
technology).
[0065] While register renaming is described in the context of
out-of-order execution, it should be understood that register
renaming may be used in an in-order architecture. While the
illustrated embodiment of the processor also includes separate
instruction and data cache units 934/974 and a shared L2 cache unit
976, alternative embodiments may have a single internal cache for
both instructions and data, such as, for example, a Level 1 (L1)
internal cache, or multiple levels of internal cache. In some
embodiments, the system may include a combination of an internal
cache and an external cache that is external to the core and/or the
processor. Alternatively, all of the cache may be external to the
core and/or the processor.
[0066] FIGS. 6 and 7 are block diagrams of a more specific
exemplary in-order core architecture, which core would be one of
several logic blocks (including other cores of the same type and/or
different types) in a chip. The logic blocks communicate through a
high-bandwidth interconnect network (e.g., a ring network) with
some fixed function logic, memory I/O interfaces, and other
necessary I/O logic, depending on the application.
[0067] FIG. 6 is a block diagram of a single processor core, along
with its connection to the on-die interconnect network 1002 and
with its local subset of the Level 2 (L2) cache 1004, according to
embodiments of the invention. In one embodiment, an instruction
decoder 1000 supports the x86 instruction set with a packed data
instruction set extension. An L1 cache 1006 allows low-latency
accesses to cache memory into the scalar and vector units. While in
one embodiment (to simplify the design), a scalar unit 1008 and a
vector unit 1010 use separate register sets (respectively, scalar
registers 1012 and vector registers 1014) and data transferred
between them is written to memory and then read back in from an L1
cache 1006, alternative embodiments of the invention may use a
different approach (e.g., use a single register set or include a
communication path that allow data to be transferred between the
two register files without being written and read back).
[0068] The local subset of the L2 cache 1004 is part of a global L2
cache that is divided into separate local subsets, one per
processor core. Each processor core has a direct access path to its
own local subset of the L2 cache 1004. Data read by a processor
core is stored in its L2 cache subset 1004 and can be accessed
quickly, in parallel with other processor cores accessing their own
local L2 cache subsets. Data written by a processor core is stored
in its own L2 cache subset 1004 and is flushed from other subsets,
if necessary. The ring network ensures coherency for shared data.
The ring network is bi-directional to allow agents such as
processor cores, L2 caches and other logic blocks to communicate
with each other within the chip. Each ring data-path is 1012-bits
wide per direction.
[0069] FIG. 7 is an expanded view of part of the processor core in
FIG. 6 according to embodiments of the invention. FIG. 7 includes
an L1 data cache 1006A part of the L1 cache 1004, as well as more
detail regarding the vector unit 1010 and the vector registers
1014. Specifically, the vector unit 1010 is a 16-wide vector
processing unit (VPU) (see the 16-wide ALU 1028), which executes
one or more of integer, single-precision float, and
double-precision float instructions. The VPU supports swizzling the
register inputs with swizzle unit 1020, numeric conversion with
numeric convert units 1022A-B, and replication with replication
unit 1024 on the memory input. Write mask registers 1026 allow
predicating resulting vector writes.
[0070] FIG. 8 is a block diagram of a processor 1100 that may have
more than one core, may have an integrated memory controller, and
may have integrated graphics according to embodiments of the
invention. The solid lined boxes in FIG. 8 illustrate a processor
1100 with a single core 1102A, a system agent 1110, a set of one or
more bus controller units 1116, while the optional addition of the
dashed lined boxes illustrates an alternative processor 1100 with
multiple cores 1102A-N, a set of one or more integrated memory
controller unit(s) in the system agent unit 1110, and special
purpose logic 1108.
[0071] Thus, different implementations of the processor 1100 may
include: 1) a CPU with the special purpose logic 1108 being
integrated graphics and/or scientific (throughput) logic (which may
include one or more cores), and the cores 1102A-N being one or more
general purpose cores (e.g., general purpose in-order cores,
general purpose out-of-order cores, a combination of the two); 2) a
coprocessor with the cores 1102A-N being a large number of special
purpose cores intended primarily for graphics and/or scientific
(throughput); and 3) a coprocessor with the cores 1102A-N being a
large number of general purpose in-order cores. Thus, the processor
1100 may be a general-purpose processor, coprocessor or
special-purpose processor, such as, for example, a network or
communication processor, compression engine, graphics processor,
GPGPU, a high-throughput many integrated core (MIC) coprocessor
(including 30 or more cores), embedded processor, or the like. The
processor may be implemented on one or more chips. The processor
1100 may be a part of and/or may be implemented on one or more
substrates using any of a number of process technologies, such as,
for example, BiCMOS, CMOS, or NMOS.
[0072] The memory hierarchy includes one or more levels of cache
units 1104A-N within the cores, a set or one or more shared cache
units 1106, and external memory (not shown) coupled to the set of
integrated memory controller units 1114. The set of shared cache
units 1106 may include one or more mid-level caches, such as L2,
level 3 (L3), level 4 (L4), or other levels of cache, a last level
cache (LLC), and/or combinations thereof. While in one embodiment a
ring based interconnect unit 1112 interconnects the special purpose
logic 1108, the set of shared cache units 1106, and the system
agent unit 1110/integrated memory controller unit(s) 1114,
alternative embodiments may use any number of well-known techniques
for interconnecting such units. In one embodiment, coherency is
maintained between one or more cache units 1106 and cores 1102
A-N.
[0073] The system agent unit 1110 includes those components
coordinating and operating cores 1102A-N. The system agent unit
1110 may include for example a power control unit (PCU) and a
display unit. The PCU may be or include logic and components needed
for regulating the power state of the cores 1102A-N and the
integrated graphics logic 1108. The display unit is for driving one
or more externally connected displays.
[0074] The cores 1102A-N may be homogenous or heterogeneous in
terms of architecture instruction set; that is, two or more of the
cores 1102A-N may be capable of execution the same instruction set,
while others may be capable of executing only a subset of that
instruction set or a different instruction set. Such cores 1102A-N
may convert certain memory access instructions into subline memory
access instructions as described herein.
[0075] FIGS. 9-11 are block diagrams of exemplary computer
architectures. Other system designs and configurations known in the
arts for laptops, desktops, handheld PCs, personal digital
assistants, engineering workstations, servers, network devices,
network hubs, switches, embedded processors, digital signal
processors (DSPs), graphics devices, video game devices, set-top
boxes, micro controllers, cell phones, portable media players, hand
held devices, and various other electronic devices, are also
suitable. In general, a huge variety of systems or electronic
devices capable of incorporating a processor and/or other execution
logic as disclosed herein are generally suitable.
[0076] FIG. 9 is a block diagram of a system 1200 according to
embodiments of the invention. The system 1200 may include one or
more processors 1210, 1215, which are coupled to a controller hub
1220. In one embodiment, the controller hub 1220 includes a
graphics memory controller hub (GMCH) 1290 and an Input/Output Hub
(IOH) 1250 (which may be on separate chips); the GMCH 1290 includes
a memory controller to control operations within a coupled memory
and a graphics controller to which are coupled memory 1240 and a
coprocessor 1245; the IOH 1250 couples input/output (I/O) devices
1260 to the GMCH 1290. Alternatively, one or both of the memory and
graphics controllers are integrated within the processor (as
described herein), the memory 1240 and the coprocessor 1245 are
coupled directly to the processor 1210, and the controller hub 1220
in a single chip with the IOH 1250.
[0077] The optional nature of additional processors 1215 is denoted
in FIG. 9 with broken lines. Each processor 1210, 1215 may include
one or more of the processing cores described herein and may be
some version of the processor 1100.
[0078] The memory 1240 may be, for example, dynamic random access
memory (DRAM), phase change memory (PCM), or a combination of the
two. For at least one embodiment, the controller hub 1220
communicates with the processor(s) 1210, 1215 via a multi-drop bus,
such as a frontside bus (FSB), point-to-point interface such as
QuickPath Interconnect (QPI), or similar connection 1295.
[0079] In one embodiment, the coprocessor 1245 is a special-purpose
processor, such as, for example, a high-throughput MIC processor, a
network or communication processor, compression engine, graphics
processor, GPGPU, embedded processor, or the like. In one
embodiment, controller hub 1220 may include an integrated graphics
accelerator.
[0080] There can be a variety of differences between the physical
resources 1210, 1215 in terms of a spectrum of metrics of merit
including architectural, microarchitectural, thermal, power
consumption characteristics, and the like.
[0081] In one embodiment, the processor 1210 executes instructions
that control data processing operations of a general type. Embedded
within the instructions may be coprocessor instructions. The
processor 1210 recognizes these coprocessor instructions as being
of a type that should be executed by the attached coprocessor 1245.
Accordingly, the processor 1210 issues these coprocessor
instructions (or control signals representing coprocessor
instructions) on a coprocessor bus or other interconnect, to
coprocessor 1245. Coprocessor(s) 1245 accept and execute the
received coprocessor instructions.
[0082] FIGS. 10 and 11 are block diagrams of more specific
exemplary systems 1300 and 1400 according to embodiments of the
invention. As shown in FIG. 10, multiprocessor system 1300 is a
point-to-point interconnect system, and includes a first processor
1370 and a second processor 1380 coupled via a point-to-point
interconnect 1350. Each of processors 1370 and 1380 may be some
version of the processor 1100. In one embodiment of the invention,
processors 1370 and 1380 are respectively processors 1210 and 1215,
while coprocessor 1338 is coprocessor 1245. In another embodiment,
processors 1370 and 1380 are respectively processor 1210 and
coprocessor 1245.
[0083] Processors 1370 and 1380 are shown including integrated
memory controller (IMC) units 1372 and 1382, respectively.
Processor 1370 also includes as part of its bus controller units
point-to-point (P-P) interfaces 1376 and 1378; similarly, second
processor 1380 includes P-P interfaces 1386 and 1388. Processors
1370, 1380 may exchange information via a P-P interface 1350 using
P-P interface circuits 1378, 1388. As shown in FIG. 10, IMCs 1372
and 1382 couple the processors to respective memories, namely a
memory 1332 and a memory 1334, which may be portions of main memory
locally attached to the respective processors.
[0084] Processors 1370, 1380 may each exchange information with a
chipset 1390 via individual P-P interfaces 1352, 1354 using point
to point interface circuits 1376, 1394, 1386, 1398. Chipset 1390
may optionally exchange information with the coprocessor 1338 via a
high-performance interface 1339. In one embodiment, the coprocessor
1338 is a special-purpose processor, such as, for example, a
high-throughput MIC processor, a network or communication
processor, compression engine, graphics processor, GPGPU, embedded
processor, or the like.
[0085] A shared cache (not shown) may be included in either
processor or outside of both processors, yet connected with the
processors via P-P interconnect, such that either or both
processors' local cache information may be stored in the shared
cache if a processor is placed into a low power mode.
[0086] Chipset 1390 may be coupled to a first bus 1316 via an
interface 1396. In one embodiment, first bus 1316 may be a
Peripheral Component Interconnect (PCI) bus, or a bus such as a PCI
Express bus or another third generation I/O interconnect bus,
although the scope of the present invention is not so limited.
[0087] As shown in FIG. 10, various I/O devices 1314 may be coupled
to first bus 1316, along with a bus bridge 1318 which couples first
bus 1316 to a second bus 1320. In one embodiment, one or more
additional processors 1315, such as coprocessors, high-throughput
MIC processors, GPGPUs, accelerators (such as, e.g., graphics
accelerators or digital signal processing (DSP) units), field
programmable gate arrays, or any other processor, are coupled to
first bus 1316. In one embodiment, second bus 1320 may be a low pin
count (LPC) bus. Various devices may be coupled to a second bus
1320 including, for example, a keyboard and/or mouse 1322,
communication devices 1327 and a storage unit 1328 such as a disk
drive or other mass storage device which may include
instructions/code and data 1330, in one embodiment. Further, an
audio I/O 1324 may be coupled to the second bus 1320. Note that
other architectures are possible. For example, instead of the
point-to-point architecture of FIG. 10, a system may implement a
multi-drop bus or other such architecture.
[0088] FIG. 11 presents a block diagram of a second more specific
exemplary system 1400 in accordance with an embodiment of the
present invention. Like elements in FIGS. 10 and 11 bear like
reference numerals, and certain aspects of FIG. 10 have been
omitted from FIG. 11 in order to avoid obscuring other aspects of
FIG. 11.
[0089] FIG. 11 illustrates that the processors 1370, 1380 may
include integrated memory and I/O control logic ("CL") 1372 and
1382, respectively. Thus, the CL 1372, 1382 include integrated
memory controller units and include I/O control logic. FIG. 11
illustrates that not only are the memories 1332, 1334 coupled to
the CL 1372, 1382, but also that I/O devices 1414 are also coupled
to the control logic 1372, 1382. Legacy I/O devices 1415 are
coupled to the chipset 1390.
[0090] FIG. 12 is a block diagram of a system on a chip (SoC) 1500
according to embodiments of the invention. Dashed lined boxes are
optional features on more advanced SoCs. In FIG. 12, an
interconnect unit(s) 1502 is coupled to: an application processor
1510 which includes a set of one or more cores 1511A-N (including
constituent cache units 1104A-N) and shared cache unit(s) 1506; a
system agent unit 1512; a bus controller unit(s) 1514; an
integrated memory controller unit(s) 1516; a set or one or more
coprocessors 1520 which may include integrated graphics logic, an
image processor, an audio processor, and a video processor; an
static random access memory (SRAM) unit 1530; a direct memory
access (DMA) unit 1532; and a display unit 1540 for coupling to one
or more external displays. In one embodiment, the coprocessor(s)
1520 include a special-purpose processor, such as, for example, a
network or communication processor, compression engine, GPGPU, a
high-throughput MIC processor, embedded processor, or the like.
[0091] In some cases, an instruction converter may be used to
convert an instruction from a source instruction set to a target
instruction set. For example, the instruction converter may
translate (e.g., using static binary translation, dynamic binary
translation including dynamic compilation), morph, emulate, or
otherwise convert an instruction to one or more other instructions
to be processed by the core. The instruction converter may be
implemented in software, hardware, firmware, or a combination
thereof. The instruction converter may be on processor, off
processor, or part on and part off processor.
CONCLUSION
[0092] In the present disclosure, expressions such as "an
embodiment," "one embodiment," and "another embodiment" are meant
to generally reference embodiment possibilities. Those expressions
are not intended to limit the invention to particular embodiment
configurations. As used herein, those expressions may reference the
same embodiment or different embodiments, and those embodiments are
combinable into other embodiments. In light of the principles and
example embodiments described and illustrated herein, it will be
recognized that the illustrated embodiments can be modified in
arrangement and detail without departing from the principles
described and/or illustrated herein.
[0093] Also, according to the present disclosure, a device may
include instructions and other data which, when accessed by a
processor, cause the device to perform particular operations. For
purposes of this disclosure, instructions which cause a device to
perform operations may be referred to in general as software.
Software and the like may also be referred to as control logic.
Software that is used during a boot process may be referred to as
firmware. Software that is stored in nonvolatile memory may also be
referred to as firmware. Software may be organized using any
suitable structure or combination of structures. Accordingly, terms
like program and module may be used in general to cover a broad
range of software constructs, including without limitation
application programs, subprograms, routines, functions, procedures,
drivers, libraries, data structures, processes, microcode, and
other types of software components. Also, it should be understood
that a software module may include more than one component, and
those components may cooperate to complete the operations of the
module. Also, the operations which the software causes a device to
perform may include creating an operating context, instantiating a
particular data structure, etc. Embodiments may be implemented as
software to execute on a programmable system comprising at least
one processor, a storage system (e.g., volatile memory and/or one
or more non-volatile storage elements), at least one input device,
and at least one output device.
[0094] Any suitable operating environment and programming language
(or combination of operating environments and programming
languages) may be used to implement software components described
herein. For example, program code may be implemented in a
high-level procedural or object oriented programming language, or
in assembly or machine language. The mechanisms described herein
are not limited to any particular programming language. In any
case, the language may be a compiled or interpreted language.
[0095] A medium which contains data and which allows another
component to obtain that data may be referred to as a
machine-accessible medium or a machine-readable medium.
Accordingly, embodiments may include machine-readable media
containing instructions for performing some or all of the
operations described herein. Such media may be referred to in
general as apparatus and in particular as program products. In one
embodiment, software for multiple components is stored in one
machine-readable medium. In other embodiments, two or more
machine-readable media may be used to store the software for one or
more components. For instance, instructions for one component may
be stored in one medium, and instructions another component may be
stored in another medium. Or a portion of the instructions for one
component may be stored in one medium, and the rest of the
instructions for that component (as well instructions for other
components), may be stored in one or more other media. Similarly,
software that is described above as residing on a particular device
in one embodiment may, in other embodiments, reside on one or more
other devices. For instance, in a distributed environment, some
software may be stored locally, and some may be stored remotely.
Similarly, operations that are described above as being performed
on one particular device in one embodiment may, in other
embodiments, be performed by one or more other devices.
[0096] Other embodiments may be implemented in data and may be
stored on a non-transitory storage medium, which if used by at
least one machine, causes the at least one machine to fabricate at
least one integrated circuit to perform one or more operations
according to the present disclosure. Still further embodiments may
be implemented in a computer readable storage medium including
information that, when manufactured into an SoC or other processor,
is to configure the SoC or other processor to perform one or more
operations according to the present disclosure. One or more aspects
of at least one embodiment may be implemented by representative
instructions, stored on a machine-readable medium, which represent
various logic units within the processor, and which, when read by a
machine, cause the machine to fabricate logic units to perform the
techniques described herein. The instructions representing various
logic units may be referred to as "IP cores," and they may be
stored on a tangible, machine readable medium and supplied to
various customers or manufacturing facilities to load into the
fabrication machines that actually make the logic units or the
processor. One or more aspects of at least one embodiment may
include machine-readable media containing instructions or design
data which defines structures, circuits, apparatuses, processors
and/or system features described herein. For instance, design data
may be formatted in a hardware description language (HDL).
[0097] The machine-readable media for some embodiments may include,
without limitation, tangible non-transitory storage components such
as magnetic disks, optical disks, magneto-optical disks, dynamic
random access memory (RAM), static RAM, read-only memory (ROM),
solid state drives (SSDs), phase change memory (PCM), etc., as well
as processors, controllers, and other components that include data
storage facilities. For purposes of this disclosure, the term "ROM"
may be used in general to refer to nonvolatile memory devices such
as erasable programmable ROM (EPROM), electrically erasable
programmable ROM (EEPROM), flash ROM, flash memory, etc.
[0098] It should also be understood that the hardware and software
components depicted herein represent functional elements that are
reasonably self-contained so that each can be designed,
constructed, or updated substantially independently of the others.
In alternative embodiments, components may be implemented as
hardware, software, or combinations of hardware and software for
providing the functionality described and illustrated herein. In
some embodiments, some or all of the control logic for implementing
the described operations may be implemented in hardware logic
(e.g., as microcode in an integrated circuit chip, as a
programmable gate array (PGA), as an application-specific
integrated circuit (ASIC), etc.). Also, terms such as "circuit" and
"circuitry" may be used interchangeably herein. Those terms and
terms like "logic" may be used to refer to analog circuitry,
digital circuitry, hard-wired circuitry, programmable circuitry,
processor circuitry, microcontroller circuitry, hardware logic
circuitry, state machine circuitry, any other type of hardware
component, or any suitable combination of hardware components.
[0099] Additionally, the present teachings may be used to advantage
in many different kinds of data processing systems. Such data
processing systems may include, without limitation, accelerators,
systems on a chip (SOCs), wearable devices, handheld devices,
smartphones, telephones, entertainment devices such as audio
devices, video devices, audio/video devices (e.g., televisions and
set-top boxes), vehicular processing systems, personal digital
assistants (PDAs), tablet computers, laptop computers, portable
computers, personal computers (PCs), workstations, servers,
client-server systems, distributed computing systems,
supercomputers, high-performance computing systems, computing
clusters, mainframe computers, mini-computers, and other devices
for processing or transmitting information. Accordingly, unless
explicitly specified otherwise or required by the context,
references to any particular type of data processing system (e.g.,
a PC) should be understood as encompassing other types of data
processing systems, as well. A data processing system may also be
referred to as an apparatus. The components of a data processing
system may also be referred to as apparatus.
[0100] Also, unless expressly specified otherwise, components that
are described as being coupled to each other, in communication with
each other, responsive to each other, or the like need not be in
continuous communication with each other and need not be directly
coupled to each other. Likewise, when one component is described as
receiving data from or sending data to another component, that data
may be sent or received through one or more intermediate
components, unless expressly specified otherwise. In addition, some
components of the data processing system may be implemented as
adapter cards with interfaces (e.g., a connector) for communicating
with a bus. Alternatively, devices or components may be implemented
as embedded controllers, using components such as programmable or
non-programmable logic devices or arrays, ASICs, embedded
computers, smart cards, and the like. For purposes of this
disclosure, the term "bus" includes pathways that may be shared by
more than two devices, as well as point-to-point pathways.
Similarly, terms such as "line," "pin," etc. should be understood
as referring to a wire, a set of wires, or any other suitable
conductor or set of conductors. For instance, a bus may include one
or more serial links, a serial link may include one or more lanes,
a lane may be composed of one or more differential signaling pairs,
and the changing characteristics of the electricity that those
conductors are carrying may be referred to as signals on a line.
Also, for purpose of this disclosure, the term "processor" denotes
a hardware component that is capable of executing software. For
instance, a processor may be implemented as a central processing
unit (CPU), a processing core, or as any other suitable type of
processing element. A CPU may include one or more processing cores,
and a device may include one or more CPUs.
[0101] Also, although one or more example processes have been
described with regard to particular operations performed in a
particular sequence, numerous modifications could be applied to
those processes to derive numerous alternative embodiments of the
present invention. For example, alternative embodiments may include
processes that use fewer than all of the disclosed operations,
process that use additional operations, and processes in which the
individual operations disclosed herein are combined, subdivided,
rearranged, or otherwise altered.
[0102] Embodiments include the following examples:
[0103] Example A1 is an integrated circuit with technology for
generating I/O latency metrics. The integrated circuit comprises an
RTC, a read measurement register, and a read latency measurement
module. The read latency measurement module comprises control logic
to perform operations comprising (a) in response to receipt of read
responses that complete read requests associated with an I/O
device, automatically calculating read latency for the completed
read requests, based at least in part on time measurements from the
RTC for initiation and completion of the read requests; (b)
automatically calculating an average read latency, based at least
in part on the calculated read latencies for the completed read
requests; and (c) automatically updating the read measurement
register to record the average read latency for the completed read
requests.
[0104] Example A2 is an integrated circuit according to Example A1,
wherein the read latency monitor further comprises control logic to
perform operations comprising: (a) automatically determining a
minimum read latency for the completed read requests, (b)
automatically determining a maximum read latency for the completed
read requests, and (c) automatically updating the read measurement
register to record the minimum read latency and the maximum read
latency.
[0105] Example A3 is an integrated circuit according to Example A1,
further comprising an I/O manager to manage the read requests.
Also, the I/O manager comprises the RTC, the read measurement
register, and the read latency measurement module. Example A3 may
also include the features of Example A2.
[0106] Example A4 is an integrated circuit according to Example A3,
wherein the I/O manager is configured to send a device read request
to the I/O device in response to receiving a host read request from
a processing core. Also, the completed read requests comprise
device read requests.
[0107] Example A5 is an integrated circuit according to Example A4,
wherein the I/O manager complies with revision 3.0 of a PCIe base
specification.
[0108] Example A6 is an integrated circuit according to Example A5,
wherein the I/O manager comprises a PCIe root complex.
[0109] Example A7 is a CPU comprising the integrated circuit
according to Example A3. The CPU also comprises a processing core
in the integrated circuit to send host read requests to the I/O
manager. Example A7 may also include the features of any one or
more of Example A2 and Examples A4 through A6.
[0110] Example A8 is a data processing system comprising the CPU
according to Example A7 and the I/O device.
[0111] Example A9 is a data processing system according to Example
A8, wherein (a) the I/O manager comprises a root port connected to
multiple I/O devices, and (b) the operation of automatically
calculating average read latency for the completed read requests
comprises of automatically calculating average read latency for
completed read requests involving any of the I/O devices connected
to the root port.
[0112] Example B1 is a data processing system with technology for
generating I/O latency metrics. The data processing system
comprises (a) an I/O manager, (b) an I/O device responsive to the
I/O manager, (c) a CPU to communicate with the I/O device via the
I/O manager, (d) an RTC in the I/O manager, (e) a read measurement
register in the I/O manager, and (f) a read latency measurement
module in the I/O manager. Also, the read latency measurement
module comprises control logic to perform operations comprising (a)
in response to receipt of read responses that complete read
requests associated with the I/O device, automatically calculating
read latency for the completed read requests, based at least in
part on time measurements from the RTC for initiation and
completion of the read requests; (b) automatically calculating an
average read latency for the completed read requests, based at
least in part on the calculated read latencies for the completed
read requests; and (c) automatically updating the read measurement
register to record the average read latency for the completed read
requests.
[0113] Example B2 is a data processing system according to Example
B1, wherein the read latency monitor further comprises control
logic to perform operations comprising (a) automatically
determining a minimum read latency for the completed read requests,
(b) automatically determining a maximum read latency for the
completed read requests, and (c) automatically updating the read
measurement register to record the minimum read latency and the
maximum read latency.
[0114] Example B3 is a data processing system ac to Example B 1,
wherein the I/O manager is configured to send a device read request
to the I/O device in response to receiving a host read request from
a processing core. Also, the completed read requests comprise
device read requests. Example B3 may also include the features of
Example B2.
[0115] Example B4 is a data processing system according to Example
B3, wherein the I/O manager complies with revision 3.0 of a PCIe
base specification.
[0116] Example B5 is a data processing system according to Example
B4, wherein the I/O manager comprises a PCIe root complex.
[0117] Example B6 is a data processing system according to Example
B 1, wherein the I/O manager comprises a root port connected to
multiple I/O devices. Also, the operation of automatically
calculating average read latency for the completed read requests
comprises of automatically calculating average read latency for
completed read requests involving any of the I/O devices connected
to the root port. Example B6 may also include the features of any
one or more of Examples B2 through B5.
[0118] Example C1 is a method for generating I/O latency metrics.
The method comprises (a) at a read latency measurement module in an
I/O manager of a data processing system, in response to receipt of
read responses that complete read requests associated with an I/O
device, automatically calculating read latencies for the completed
read requests, based at least in part on time measurements from an
RTC for initiation and completion of the read requests; (b) at the
read latency measurement module, automatically calculating an
average read latency for the completed read requests, based at
least in part on the calculated read latencies for the completed
read requests; and (c) automatically updating a read measurement
register in the I/O manager to record the average read latency for
the completed read requests.
[0119] Example C2 is a method according to Example C1, further
comprising (a) at the read latency measurement module,
automatically determining a minimum read latency for the completed
read requests and automatically determining a maximum read latency
for the completed read requests; and (b) automatically updating the
read measurement register to record the minimum read latency and
the maximum read latency.
[0120] Example C3 is a method according to Example C1, further
comprising (a) at the I/O manager, receiving a host read request
from a processing core of the data processing system; and (b)
automatically sending a device read request from the I/O manager to
the I/O device, in response to receiving the host read request from
the processing core. Also, the completed read requests comprise
device read requests. Example C3 may also include the features of
Example C2.
[0121] Example C4 is a method according to Example C3, further
comprising, at the I/O manager, managing read requests as a PCIe
root complex, in accordance with revision 3.0 of a PCIe base
specification.
[0122] Example C5 is a method according to Example C1, further
comprising receiving the read responses via a root port of the I/O
manager that is connected to multiple I/O devices. Also, the
operation of automatically calculating average read latency for the
completed read requests comprises of automatically calculating
average read latency for completed read requests involving any of
the I/O devices connected to the root port. Example C5 may also
include the features of any one or more of Examples C2 through
C4.
[0123] Example D1 is an integrated circuit with technology for
generating I/O latency metrics. The integrated circuit comprises an
I/O manager to manage read requests, wherein the I/O manager
complies with revision 3.0 of a Peripheral Component Interconnect
Express (PCIe) base specification. The integrated circuit further
comprises (a) an RTC in the I/O manager, a read measurement
register in the I/O manager, and a read latency measurement module
in the I/O manager. The read latency measurement module comprises
control logic to perform operations comprising (a) in response to
receipt of read responses that complete read requests associated
with an I/O device, automatically calculating read latency for the
completed read requests, based at least in part on time
measurements from the RTC for initiation and completion of the read
requests; (b) automatically calculating an average read latency for
the completed read requests, based at least in part on the
calculated read latencies for the completed read requests; and (c)
automatically updating the read measurement register to record the
average read latency for the completed read requests.
[0124] Example D2 is an integrated circuit according to Example D1,
wherein the read latency monitor further comprises control logic to
perform operations comprising (a) automatically determining a
minimum read latency for the completed read requests; (b)
automatically determining a maximum read latency for the completed
read requests; and (c) automatically updating the read measurement
register to record the minimum read latency and the maximum read
latency.
[0125] Example D3 is an integrated circuit according to Example D1,
wherein the I/O manager comprises a PCIe root complex. Example D3
may also include the features of Example D2.
[0126] In view of the wide variety of useful permutations that may
be readily derived from the example embodiments described herein,
this detailed description is intended to be illustrative only, and
should not be construed as limiting the scope of coverage.
* * * * *