U.S. patent application number 15/203108 was filed with the patent office on 2016-10-27 for systems and methods for dynamic priority control.
The applicant listed for this patent is Marvell World Trade Ltd.. Invention is credited to Joseph Jun Cao, Ruoyang Lu, Tsung-Ju Yang, Jun Zhu.
Application Number | 20160313949 15/203108 |
Document ID | / |
Family ID | 48325782 |
Filed Date | 2016-10-27 |
United States Patent
Application |
20160313949 |
Kind Code |
A1 |
Zhu; Jun ; et al. |
October 27, 2016 |
Systems and Methods for Dynamic Priority Control
Abstract
System and methods are provided for dynamically managing a
first-in/first-out (FIFO) command queue of a system controller. One
or more commands are received into the command queue, a command
being associated with a priority parameter. A current command first
in line to be executed in the command queue is determined, the
current command being associated with a first priority parameter. A
second command associated with a second priority parameter is
determined, the second priority parameter being largest among
priority parameters associated with the one or more commands. A
final priority parameter for the current command is computed based
at least in part on the second priority parameter.
Inventors: |
Zhu; Jun; (San Jose, CA)
; Cao; Joseph Jun; (Los Gatos, CA) ; Yang;
Tsung-Ju; (San Jose, CA) ; Lu; Ruoyang; (San
Jose, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Marvell World Trade Ltd. |
St. Michael |
|
BB |
|
|
Family ID: |
48325782 |
Appl. No.: |
15/203108 |
Filed: |
July 6, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14861168 |
Sep 22, 2015 |
9411753 |
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15203108 |
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13750053 |
Jan 25, 2013 |
9146690 |
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14861168 |
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61591705 |
Jan 27, 2012 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G06F 3/0659 20130101;
G06F 3/0673 20130101; G06F 13/1642 20130101; G06F 3/061
20130101 |
International
Class: |
G06F 3/06 20060101
G06F003/06; G06F 13/16 20060101 G06F013/16 |
Claims
1. (canceled)
2. A method comprising: receiving a plurality of commands into a
FIFO queue, wherein each command of the plurality of commands has a
priority value, and the plurality of commands include a current
command that corresponds to a command that is currently first in
line in the queue to be executed: determining a queue priority
value for the queue as an average of the priority values of the
plurality of commands; and scheduling execution of the current
command based on the queue priority value.
3. The method of claim 2, wherein the method further comprises,
after scheduling execution of the current command: executing the
current command and removing the current command from the queue;
and in response to the removal of the current command, determining
a new queue priority value for the queue as an average of commands
that are in the queue.
4. The method of claim 3, wherein the new queue priority value is
lower than the previously determined queue priority value.
5. The method of claim 2, wherein the plurality of commands include
a highest priority command that is later in the queue than the
current command and whose priority value is the highest priority
value in the queue.
6. The method of claim 5, wherein the method further comprises,
after scheduling execution of the current command: executing the
highest priority command and removing the highest priority command
from the queue; and determining a new queue priority value for the
queue as an average of priority values of commands that are in the
queue, wherein the new queue priority value is lower than the
previously determined queue priority value.
7. The method of claim 5, further comprising, after the scheduling
execution of the current command: determining a wait time
indicating an amount of time the highest priority command has been
in the queue; in response to the wait time exceeding a
predetermined threshold, determining a new queue priority value as
equal to the priority value of the highest priority command.
8. The method of claim 5, wherein determining the queue priority
value includes: determining a wait time indicating an amount of
time the highest priority command has been in the queue; if the
wait time does not exceed a predetermined threshold, then
determining the queue priority value as an average of the priority
values of the plurality of commands; and if the wait time does
exceed the predetermined threshold, then determining the queue
priority value as equal to the priority value of the highest
priority command.
9. The method of claim 5, further comprising: maintaining, for each
command of the plurality of commands, a wan time indicating an
amount of time the respective command has been in the queue;
wherein determining the queue priority value is at least partially
based on the wait time of at least one of the commands.
10. The method of claim 9, wherein determining the queue priority
value is at least partially based on wait times of two or more of
the commands.
11. The method of claim 9, wherein maintaining the wait times is
hardware implemented.
12. The method of claim 2, further comprising, after scheduling
execution of the current command from the queue: adding a new
command to the queue; and in response to adding a new command to
the queue, determining a new queue priority value for the queue as
an average of priority values of commands that are in the
queue.
13. The method of claim 12, wherein the new queue priority is lower
than the previously determined queue priority value.
14. The method of claim 12, wherein the new queue priority is
higher than the previously determined queue priority value.
15. An integrated circuit for dynamically scheduling execution of a
command from a first in/first-out (FIFO) queue, the integrated
circuit comprising: a memory configured to receive a plurality of
commands into the FIFO queue, wherein each command of the plurality
of commands has a priority value, and the plurality of commands
include a current command that corresponds to a command that is
currently first in line in the queue to be executed; an arbitrator
configured to determine a queue priority value for the queue as an
average of the priority values of the plurality of commands; and a
scheduler configured to schedule execution of the current command
from the queue based on the queue priority value.
16. The integrated circuit of claim 15, wherein the integrated
circuit further comprises a processor configured to execute the
current command and remove the current command from the queue, and
wherein the arbitrator is further configured to, in response to
removal of the current command, determine a new queue priority
value for the queue as an average of commands that are in the
queue.
17. The integrated circuit of claim 16, wherein the arbitrator is
configured to determine the new queue priority value as a lower
value than the previously determined queue priority value.
18. The integrated circuit of claim 15, wherein the plurality of
commands that the memory is configured to receive include a highest
priority command that is later in the queue than the current
command and whose priority value is the highest priority value in
the
19. The integrated circuit of claim 18, wherein the integrated
circuit further comprises a processor configured to execute the
highest priority command and remove the highest priority command
from the queue, and wherein the arbitrator is configured to
determine a new queue priority value for the queue as an average
priority values of commands that are in the queue, and Wherein the
new queue priority value is lower than the previously determined
queue priority value.
20. The integrated circuit of claim 18, wherein the integrated
circuit is configured to determine a wait time indicating an amount
of time the highest priority command has been in the FIFO queue,
and wherein the arbitrator is configured to, in response to the
wait time exceeding a predetermined threshold, determine a new
queue priority value as equal to the priority value of the highest
priority command.
21. A non-transitory processor readable medium storing instructions
configured to be executed by one or more processors to: receive a
plurality of commands into a FIFO queue, wherein each command of
the plurality of commands respectively has a priority value, and
the plurality of commands include a current command that
corresponds to a command that is currently first in line in the
queue to be executed; determine a queue priority value for the
queue as an average of the priority values of the plurality of
commands; and schedule execution of the current command based on
the queue priority value.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This is a continuation of U.S. application Ser. No.
14/861,168, filed Sep. 22, 2015, which is a continuation of U.S.
application Ser. No. 13/750,053 (now U.S. Pat. No. 9,146,690),
filed Jan. 25, 2013, which claims priority from US Provisional
Application No. 61/591705, filed Jan. 27, 2012. The above
applications are hereby incorporated herein by reference.
FIELD
[0002] The technology described in this patent document relates
generally to data processing and more particularly to priority
control in data processing.
BACKGROUND
[0003] A memory system often includes semiconductor memory devices,
such as dynamic random access memory (DRAM), synchronous DRAM
(SDRAM), double data rate (DDR, DDR2, DDR3, etc.) SDRAM, etc.
Various source devices, such as processors, peripheral devices
(e.g., input/output devices), audio and video devices, may generate
memory operation commands, including read memory operations to
transfer data from memory devices to the source devices and write
memory operations to transfer data from the source devices to the
memory devices. Usually, a memory controller is implemented to
receive the memory operation commands from the source devices and
to control the memory devices to perform memory operations in
response to the commands. The memory controller often includes
command queues to capture the memory operation commands.
[0004] Priority parameters (e.g., Quality of Service (QoS)
parameters) of the memory operation commands may be transmitted as
parts of the commands to the memory controller. The memory
controller may arbitrate among memory operation commands from
different command queues and schedule execution of such commands
based on their respective priority parameters. FIG. 1 illustrates
an example of a memory controller scheduling execution of memory
operation commands. An arbiter component 108 in a memory controller
100 schedules execution of memory operation commands 104 from
multiple command queues 102 based on priority parameters 106 of the
memory operation commands 104. As shown in FIG. 1, the memory
controller 100 includes multiple system interface ports (SIPs) 110
which correspond to multiple command queues 102 respectively. A
command queue stores one or more memory operation commands 104
which each include a priority parameter 106 (e.g., QoS). Each
command queue has a current command which is at the top of the
command queue and thus first in line to be serviced. The arbiter
component 108 compares the priority parameters (e.g., QoS) of the
current commands in different command queues, and selects one
current command with a highest priority parameter to be serviced.
For example, a command queue often operates in a first-in-first-out
(FIFO) manner. That is, a current command of a command queue is the
one that is received earlier than other commands in the command
queue.
SUMMARY
[0005] In accordance with the teachings described herein, systems
and methods are provided for dynamically managing a
first-in/first-out (FIFO) command queue of a system controller. One
or more commands are received into the command queue, a command
being associated with a priority parameter. A current command first
in line to be executed in the command queue is determined, the
current command being associated with a first priority parameter. A
second command associated with a second priority parameter is
determined, the second priority parameter being largest among
priority parameters associated with the one or more commands. A
final priority parameter for the current command is computed based
at least in part on the second priority parameter.
[0006] In another embodiment, an integrated circuit for dynamically
managing a first-in/first-out (FIFO) command queue of a system
controller includes, an interface circuit configured to receive one
or more commands into the command queue, a command being associated
with a priority parameter, a monitoring circuit configured to
determine a current command first in line to be executed in the
command queue, the current command being associated with a first
priority parameter, and determine a second command associated with
a second priority parameter, the second priority parameter being
largest among priority parameters associated with the one or more
commands, and a selection circuit configured to compute a final
priority parameter for the current command based at least in part
on the second priority parameter and output the final priority
parameter in order for the current command to be selected for
execution when the final priority parameter satisfies a
predetermined condition.
[0007] In yet another embodiment, a system for dynamically managing
a first-in/first-out (FIFO) command queue of a system controller
includes one or more data processors, and a computer-readable
memory encoded with programming instructions for commanding the one
or more data processors to perform steps. The steps include,
receiving one or more commands into the command queue, a command
being associated with a priority parameter, determining a current
command first in line to be executed in the command queue, the
current command being associated with a first priority parameter,
and determining a second command associated with a second priority
parameter, the second priority parameter being largest among
priority parameters associated with the one or more commands. The
steps further include computing a final priority parameter for the
current command based at least in part on the second priority
parameter, and outputting the final priority parameter in order for
the current command to be selected for execution when the final
priority parameter satisfies a predetermined condition.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 illustrates an example of a memory controller
scheduling execution of memory operation commands.
[0009] FIG. 2 illustrates an example of a FIFO command queue.
[0010] FIG. 3 illustrates an example of generating dynamic priority
parameters for commands in a command queue.
[0011] FIG. 4 illustrates another example of generating dynamic
priority parameters for commands in a command queue.
[0012] FIG. 5 illustrates example data fields of commands in a
command queue for generating dynamic priority parameters.
[0013] FIG. 6 illustrates an example of a memory controller
scheduling execution of memory operation commands based on dynamic
priority parameters associated with command queues.
DETAILED DESCRIPTION
[0014] Referring back to FIG. 1, the arbiter component 108 selects
one of multiple current commands which has a highest priority
parameter to be serviced. Thus, if a current command of a
particular command queue has a low priority parameter, then such a
current command may need to wait for a long period of time before
it can be serviced. Other commands in the command queue are blocked
by the current command, even though they may have high priority
parameters.
[0015] FIG. 2 illustrates an example of a FIFO command queue.
Commands with high priority parameters (e.g., command 204) are
blocked by a current command 202 with a low priority parameter. As
shown in FIG. 2, a memory operation command includes an
identification number ("ID") for ordering control, an address
("Addr") indicating a memory location for accessing data in the
memory, and a priority parameter ("QoS") indicating how urgent the
command is. A memory operation command 202 with a low priority
parameter "1" (e.g., QoS) stays at the top of the command queue 200
and is the current command of the command queue 200. Because the
current command 202 has a low priority parameter, it may not be
serviced for a long time. Thus, even though other commands in the
command queue 200 may have high priority parameters, they cannot
get serviced. For example, another memory operation command 204 has
a very high priority parameter "15" (e.g., QoS). However, the
command 204 is in the middle of the command queue 200, and thus it
will not have a chance to be serviced until all commands before the
command 204 have been serviced.
[0016] As an example, a Liquid Crystal Display (LCD) controller
sends commands to read data from a memory. At first, a LCD buffer
has enough data to be displayed, and the LCD controller sends read
commands with low priority parameters (e.g., QoS) to a command
queue associated with the LCD. The memory controller does not
service these read commands in time because commands from other
command queues may have higher priority parameters. Later when the
buffer does not have enough data to be displayed, the LCD
controller sends read commands with high priority parameters to the
same command queue associated with the LCD. The previous read
commands with low priority parameters are still in the command
queue waiting for execution, and block the subsequent read commands
with high priority parameters. Then, error may occur when the
buffer has no data to be displayed.
[0017] A virtual channel approach or a multi-channel approach which
often uses multiple physical command queues for a particular system
interface port may ameliorate the problem, since commands with
different priority parameters may be input into different command
queues and the commands with high priority parameters may not be
blocked by the commands with low priority parameters. However, the
implementation of the virtual channel approach or the multi-channel
approach is very expensive. In addition, such virtual channel
approach or multi-channel approach will typically encounter a
different problem.
[0018] Often, a source device needs to access a number of
consecutive locations of the memory. For each location, the source
device usually sends out a command. These commands from the source
device share a same identification number. Usually, it is preferred
to execute these commands in the order that they are sent out, so
that the target locations of the memory can be accessed
consecutively. A single FIFO command queue for a particular system
interface port can often achieve this without any problem because
the commands received first will be serviced first. However, under
the virtual channel approach or the multi-channel approach,
commands with the same identification number are often sent to
different physical command queues. Additional mechanisms are
usually needed to execute commands with the same identification
number in order, which will increase the complexity and cost of the
system.
[0019] The present disclosure presents an approach allowing
commands in a command queue to be serviced in time according to the
status of the command queue. FIG. 3 illustrates an example of
generating dynamic priority parameters for commands in a command
queue. An arbiter component 302 receives a dynamic priority
parameter 304 ("QoS_arb") determined based on the status of a
command queue 306. If the dynamic priority parameter 304 is higher
than other priority parameters associated with other command
queues, the arbiter component 302 selects a current command 308 of
the command queue 306 to be serviced. When commands with high
priority parameters are received into the command queue 306 later
than the current command 308, the dynamic priority parameter 304 is
increased to speed up the service of the command queue 306. When
the commands with high priority parameters are serviced, the
dynamic priority parameter 304 is reduced to slow down the service
of the command queue 306.
[0020] Specifically, an algorithm may be implemented to dynamically
determine a highest priority parameter in the command queue 306.
How long the command with the highest priority parameter has stayed
in the command queue 306 may be taken into account to determine the
dynamic priority parameter 304. As an example, a command 318 is
determined to have a highest priority parameter 316 ("QoS_Max") in
the command queue 306. If the command 318 has stayed in the command
queue 306 longer than a wait-time threshold, the dynamic priority
parameter 304 is determined to be equal to the highest priority
parameter 316 ("QoS_Max"). On the other hand, if the command 318
has stayed in the command queue 306 no longer than the wait-time
threshold, the dynamic priority parameter 304 is determined to be
equal to half of a sum of the highest priority parameter 316
("QoS_Max") and a current priority parameter 314 of a current
command 308. Alternatively, in some circumstances, the dynamic
priority parameter 304 is determined to be equal to the highest
priority parameter 316 ("QoS_Max") regardless of how long the
command 318 has stayed in the command queue 306.
[0021] FIG. 4 illustrates another example of generating dynamic
priority parameters for commands in a command queue. As shown in
FIG. 4, a selection component 610 (e.g., a programmable register)
outputs a signal 622 ("QoS_sel") to a multiplexer 612 to select one
of three modes for generating a dynamic priority parameter 604 for
a command queue 606. Under a first mode, the dynamic priority
parameter 604 is always determined to be equal to a current
priority parameter 614 of a current command 608 in the command
queue 606. Under a second mode, the dynamic priority parameter 604
is always determined to be equal to a highest priority parameter
616 in the command queue 606. Further, under a third mode, the
multiplexer 612 outputs a modified priority parameter 620 ("QoS'")
as the dynamic priority parameter 604.
[0022] For example, the modified priority parameter 620 may be
determined based on how long a command 618 with the highest
priority parameter 616 has stayed in the command queue 606. If the
command 618 has stayed in the command queue 606 longer than a first
wait-time threshold, the modified priority parameter 620 is
determined to be equal to the maximum priority parameter 616. On
the other hand, if the command 618 has stayed in the command queue
606 no longer than the first wait-time threshold, the modified
priority parameter 620 is determined to be equal to half of a sum
of the maximum priority parameter 616 and the current priority
parameter 614.
[0023] Further, how long the current command 608 has stayed in the
command queue 606 may also be taken into account to determine the
modified priority parameter 620. As an example, if the command 618
has stayed in the command queue 606 longer than the first wait-time
threshold and the current command 608 has stayed in the command
queue 606 longer than a second wait-time threshold, the modified
priority parameter 620 is determined to be equal to a first value.
If the command 618 has stayed in the command queue 606 no longer
than the first wait-time threshold and the current command 608 has
stayed in the command queue 606 longer than a second wait-time
threshold, the modified priority parameter 620 is determined to be
equal to a second value. If the command 618 has stayed in the
command queue 606 longer than the first wait-time threshold and the
current command 608 has stayed in the command queue 606 no longer
than a second wait-time threshold, the modified priority parameter
620 is determined to be equal to a third value. In addition, if the
command 618 has stayed in the command queue 606 no longer than the
first wait-time threshold and the current command 608 has stayed in
the command queue 606 no longer than a second wait-time threshold,
the modified priority parameter 620 is determined to be equal to a
fourth value. For example, the first value and the third value are
equal to the maximum priority parameter 616, and the second value
and the fourth value are equal to half of the sum of the maximum
priority parameter 616 and the current priority parameter 614.
[0024] FIG. 5 illustrates example data fields of commands in a
command queue for generating dynamic priority parameters. Each
command in a command queue 400 includes three data fields related
to generating dynamic priority parameters--a validity factor ("V")
indicating whether the command is valid, a wait-time factor ("WT")
indicating a wait time of the command (i.e., how long the command
stays in the command queue 400), and an original priority parameter
("QoS_org"). For example, when the validity factor of a command is
1, the command is valid, and when the validity factor is 0, the
command is invalid. The wait-time factor of a valid command begins
to increase when the command is received into the command queue 400
until reaching a maximum value, and is cleared when the command is
popped out of the command queue 400. A read pointer 410 ("rd_ptr")
points to a current command 412, and increases by one when the
current command 412 is popped out of the command queue 400. A write
pointer 408 ("wr_ptr") points to a next available location in the
command queue 400 for receiving a new command, and increases by one
when a new command is received. As an example, the command queue
400 is managed in a circular FIFO manner.
[0025] A two-dimensional array, QoS
Info[Q_Size-1:0][Entry_Size-1:0], may be defined to store
information of the above-noted data fields for generating dynamic
priority parameters, where Q_Size indicates how many commands can
be stored in the command queue 400, and Entry_Size represents a sum
of sizes of a validity factor, a wait-time factor and an original
priority parameter.
[0026] A maximum priority parameter of valid commands in the
command queue 400 can be determined as follows:
TABLE-US-00001 QoS_max=0; max_loc=0; For (i=0; i<Q_Size; i++){
if ((QoS max<QoS_Info[i].QoS_org) & (QoS_info[i].V==1))
QoS_max=QoS_info[i].QoS_org, max_loc=i; }
[0027] A wait-time factor of a command having the maximum priority
parameter is determined as follows:
WT_Max_QoS=QoS_Info[max_loc].WT
A wait-time factor of the current command is determined as
follows:
WT_Cur=QoS_Info[rd_ptr].WT
[0028] For the first mode as discussed in FIG. 3, the dynamic
priority parameter is determined as follows:
QoS'=QoS_Info[rd_ptr].QoS_org
[0029] For the second mode, the dynamic priority parameter is
determined as follows:
QoS'=QoS_max
In addition, for the third mode, the dynamic priority parameter is
determined based on the first wait-time threshold ("THR1") and the
second wait-time threshold ("THR2") as follows:
TABLE-US-00002 WT_Max_QoS > THR1 WT_Cur > THR2 QoS' Yes Yes
QoS_Max No Yes (QoS_Max + QoS_Cur)/2 Yes No QoS_Max No No (QoS_Max
+ QoS_Cur)/2
[0030] FIG. 6 illustrates an example of a memory controller
scheduling execution of memory operation commands based on dynamic
priority parameters associated with command queues. An arbiter
component 502 in a memory controller 500 schedules execution of
memory operation commands from multiple command queues 504 based on
dynamic priority parameters 506 ("QoS_arb") associated with the
command queues 504 respectively. The arbiter component 502 compares
the dynamic priority parameters 506 ("QoS_arb") associated with the
command queues 504, and selects, through a multiplexer 510, a
current command of a command queue that has a highest dynamic
priority parameter. The selected current command is output to a
memory command scheduler 512 (e.g., a DDR command scheduler) to be
serviced. The command queues 504 correspond to multiple system
interface ports (SIPs) 508 respectively.
[0031] This written description uses examples to disclose the
invention, include the best mode, and also to enable a person
skilled in the art to make and use the invention. The patentable
scope of the invention may include other examples that occur to
those skilled in the art. For example, the systems and methods
described herein may be implemented for priority control in any
system controller with a single-command-queue structure. As an
example, the systems and methods described herein may be
implemented for priority control in modules or components of a
system-on-a-chip (SOC), such as SOC fabrics (bus interconnects),
PCIe modules, and USB modules in the SOC.
[0032] For example, the systems and methods described herein may be
implemented on many different types of processing devices by
program code comprising program instructions that are executable by
the device processing subsystem. Other implementations may also be
used, however, such as firmware or appropriately designed hardware
configured to carry out the methods and systems described herein.
In another example, the systems and methods described herein may be
implemented in an independent processing engine, as a co-processor,
or as a hardware accelerator. In yet another example, the systems
and methods described herein may be provided on many different
types of computer-readable media including computer storage
mechanisms (e.g., CD-ROM, diskette, RAM, flash memory, computer's
hard drive, etc.) that contain instructions (e.g., software) for
use in execution by a processor to perform the methods' operations
and implement the systems described herein.
* * * * *