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Diffstat (limited to 'Documentation/admin-guide/pm/amd-pstate.rst')
| -rw-r--r-- | Documentation/admin-guide/pm/amd-pstate.rst | 400 |
1 files changed, 384 insertions, 16 deletions
diff --git a/Documentation/admin-guide/pm/amd-pstate.rst b/Documentation/admin-guide/pm/amd-pstate.rst index 83b58eb4ab4d..1e0d101b020a 100644 --- a/Documentation/admin-guide/pm/amd-pstate.rst +++ b/Documentation/admin-guide/pm/amd-pstate.rst @@ -182,6 +182,7 @@ to the ``struct sugov_cpu`` that the utilization update belongs to. Then, ``amd-pstate`` updates the desired performance according to the CPU scheduler assigned. +.. _processor_support: Processor Support ======================= @@ -229,8 +230,8 @@ with :c:macro:`MSR_AMD_CPPC_ENABLE` or ``cppc_set_enable``, it will respond to the request from AMD P-States. -User Space Interface in ``sysfs`` -================================== +User Space Interface in ``sysfs`` - Per-policy control +====================================================== ``amd-pstate`` exposes several global attributes (files) in ``sysfs`` to control its functionality at the system level. They are located in the @@ -261,6 +262,25 @@ lowest non-linear performance in `AMD CPPC Performance Capability <perf_cap_>`_.) This attribute is read-only. +``energy_performance_available_preferences`` + +A list of all the supported EPP preferences that could be used for +``energy_performance_preference`` on this system. +These profiles represent different hints that are provided +to the low-level firmware about the user's desired energy vs efficiency +tradeoff. ``default`` represents the epp value is set by platform +firmware. This attribute is read-only. + +``energy_performance_preference`` + +The current energy performance preference can be read from this attribute. +and user can change current preference according to energy or performance needs +Please get all support profiles list from +``energy_performance_available_preferences`` attribute, all the profiles are +integer values defined between 0 to 255 when EPP feature is enabled by platform +firmware, if EPP feature is disabled, driver will ignore the written value +This attribute is read-write. + Other performance and frequency values can be read back from ``/sys/devices/system/cpu/cpuX/acpi_cppc/``, see :ref:`cppc_sysfs`. @@ -279,25 +299,146 @@ module which supports the new AMD P-States mechanism on most of the future AMD platforms. The AMD P-States mechanism is the more performance and energy efficiency frequency management method on AMD processors. -Kernel Module Options for ``amd-pstate`` -========================================= -``shared_mem`` -Use a module param (shared_mem) to enable related processors manually with -**amd_pstate.shared_mem=1**. -Due to the performance issue on the processors with `Shared Memory Support -<perf_cap_>`_, we disable it presently and will re-enable this by default -once we address performance issue with this solution. +``amd-pstate`` Driver Operation Modes +====================================== + +``amd_pstate`` CPPC has 3 operation modes: autonomous (active) mode, +non-autonomous (passive) mode and guided autonomous (guided) mode. +Active/passive/guided mode can be chosen by different kernel parameters. + +- In autonomous mode, platform ignores the desired performance level request + and takes into account only the values set to the minimum, maximum and energy + performance preference registers. +- In non-autonomous mode, platform gets desired performance level + from OS directly through Desired Performance Register. +- In guided-autonomous mode, platform sets operating performance level + autonomously according to the current workload and within the limits set by + OS through min and max performance registers. + +Active Mode +------------ + +``amd_pstate=active`` + +This is the low-level firmware control mode which is implemented by ``amd_pstate_epp`` +driver with ``amd_pstate=active`` passed to the kernel in the command line. +In this mode, ``amd_pstate_epp`` driver provides a hint to the hardware if software +wants to bias toward performance (0x0) or energy efficiency (0xff) to the CPPC firmware. +then CPPC power algorithm will calculate the runtime workload and adjust the realtime +cores frequency according to the power supply and thermal, core voltage and some other +hardware conditions. + +Passive Mode +------------ + +``amd_pstate=passive`` + +It will be enabled if the ``amd_pstate=passive`` is passed to the kernel in the command line. +In this mode, ``amd_pstate`` driver software specifies a desired QoS target in the CPPC +performance scale as a relative number. This can be expressed as percentage of nominal +performance (infrastructure max). Below the nominal sustained performance level, +desired performance expresses the average performance level of the processor subject +to the Performance Reduction Tolerance register. Above the nominal performance level, +processor must provide at least nominal performance requested and go higher if current +operating conditions allow. + +Guided Mode +----------- + +``amd_pstate=guided`` + +If ``amd_pstate=guided`` is passed to kernel command line option then this mode +is activated. In this mode, driver requests minimum and maximum performance +level and the platform autonomously selects a performance level in this range +and appropriate to the current workload. + +``amd-pstate`` Preferred Core +================================= + +The core frequency is subjected to the process variation in semiconductors. +Not all cores are able to reach the maximum frequency respecting the +infrastructure limits. Consequently, AMD has redefined the concept of +maximum frequency of a part. This means that a fraction of cores can reach +maximum frequency. To find the best process scheduling policy for a given +scenario, OS needs to know the core ordering informed by the platform through +highest performance capability register of the CPPC interface. + +``amd-pstate`` preferred core enables the scheduler to prefer scheduling on +cores that can achieve a higher frequency with lower voltage. The preferred +core rankings can dynamically change based on the workload, platform conditions, +thermals and ageing. + +The priority metric will be initialized by the ``amd-pstate`` driver. The ``amd-pstate`` +driver will also determine whether or not ``amd-pstate`` preferred core is +supported by the platform. + +``amd-pstate`` driver will provide an initial core ordering when the system boots. +The platform uses the CPPC interfaces to communicate the core ranking to the +operating system and scheduler to make sure that OS is choosing the cores +with highest performance firstly for scheduling the process. When ``amd-pstate`` +driver receives a message with the highest performance change, it will +update the core ranking and set the cpu's priority. + +``amd-pstate`` Preferred Core Switch +===================================== +Kernel Parameters +----------------- + +``amd-pstate`` peferred core`` has two states: enable and disable. +Enable/disable states can be chosen by different kernel parameters. +Default enable ``amd-pstate`` preferred core. + +``amd_prefcore=disable`` + +For systems that support ``amd-pstate`` preferred core, the core rankings will +always be advertised by the platform. But OS can choose to ignore that via the +kernel parameter ``amd_prefcore=disable``. + +User Space Interface in ``sysfs`` - General +=========================================== + +Global Attributes +----------------- + +``amd-pstate`` exposes several global attributes (files) in ``sysfs`` to +control its functionality at the system level. They are located in the +``/sys/devices/system/cpu/amd_pstate/`` directory and affect all CPUs. -To check whether the current processor is using `Full MSR Support <perf_cap_>`_ -or `Shared Memory Support <perf_cap_>`_ : :: +``status`` + Operation mode of the driver: "active", "passive" or "disable". - ray@hr-test1:~$ lscpu | grep cppc - Flags: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt pdpe1gb rdtscp lm constant_tsc rep_good nopl nonstop_tsc cpuid extd_apicid aperfmperf rapl pni pclmulqdq monitor ssse3 fma cx16 sse4_1 sse4_2 x2apic movbe popcnt aes xsave avx f16c rdrand lahf_lm cmp_legacy svm extapic cr8_legacy abm sse4a misalignsse 3dnowprefetch osvw ibs skinit wdt tce topoext perfctr_core perfctr_nb bpext perfctr_llc mwaitx cpb cat_l3 cdp_l3 hw_pstate ssbd mba ibrs ibpb stibp vmmcall fsgsbase bmi1 avx2 smep bmi2 erms invpcid cqm rdt_a rdseed adx smap clflushopt clwb sha_ni xsaveopt xsavec xgetbv1 xsaves cqm_llc cqm_occup_llc cqm_mbm_total cqm_mbm_local clzero irperf xsaveerptr rdpru wbnoinvd cppc arat npt lbrv svm_lock nrip_save tsc_scale vmcb_clean flushbyasid decodeassists pausefilter pfthreshold avic v_vmsave_vmload vgif v_spec_ctrl umip pku ospke vaes vpclmulqdq rdpid overflow_recov succor smca fsrm + "active" + The driver is functional and in the ``active mode`` -If the CPU flags have ``cppc``, then this processor supports `Full MSR Support -<perf_cap_>`_. Otherwise, it supports `Shared Memory Support <perf_cap_>`_. + "passive" + The driver is functional and in the ``passive mode`` + "guided" + The driver is functional and in the ``guided mode`` + + "disable" + The driver is unregistered and not functional now. + + This attribute can be written to in order to change the driver's + operation mode or to unregister it. The string written to it must be + one of the possible values of it and, if successful, writing one of + these values to the sysfs file will cause the driver to switch over + to the operation mode represented by that string - or to be + unregistered in the "disable" case. + +``prefcore`` + Preferred core state of the driver: "enabled" or "disabled". + + "enabled" + Enable the ``amd-pstate`` preferred core. + + "disabled" + Disable the ``amd-pstate`` preferred core + + + This attribute is read-only to check the state of preferred core set + by the kernel parameter. ``cpupower`` tool support for ``amd-pstate`` =============================================== @@ -393,6 +534,230 @@ about part of the output. :: CPU_005 712 116384 39 49 166 0.7565 9645075 2214891 38431470 25.1 11.646 469 2.496 kworker/5:0-40 CPU_006 712 116408 39 49 166 0.6769 8950227 1839034 37192089 24.06 11.272 470 2.496 kworker/6:0-1264 +Unit Tests for amd-pstate +------------------------- + +``amd-pstate-ut`` is a test module for testing the ``amd-pstate`` driver. + + * It can help all users to verify their processor support (SBIOS/Firmware or Hardware). + + * Kernel can have a basic function test to avoid the kernel regression during the update. + + * We can introduce more functional or performance tests to align the result together, it will benefit power and performance scale optimization. + +1. Test case descriptions + + 1). Basic tests + + Test prerequisite and basic functions for the ``amd-pstate`` driver. + + +---------+--------------------------------+------------------------------------------------------------------------------------+ + | Index | Functions | Description | + +=========+================================+====================================================================================+ + | 1 | amd_pstate_ut_acpi_cpc_valid || Check whether the _CPC object is present in SBIOS. | + | | || | + | | || The detail refer to `Processor Support <processor_support_>`_. | + +---------+--------------------------------+------------------------------------------------------------------------------------+ + | 2 | amd_pstate_ut_check_enabled || Check whether AMD P-State is enabled. | + | | || | + | | || AMD P-States and ACPI hardware P-States always can be supported in one processor. | + | | | But AMD P-States has the higher priority and if it is enabled with | + | | | :c:macro:`MSR_AMD_CPPC_ENABLE` or ``cppc_set_enable``, it will respond to the | + | | | request from AMD P-States. | + +---------+--------------------------------+------------------------------------------------------------------------------------+ + | 3 | amd_pstate_ut_check_perf || Check if the each performance values are reasonable. | + | | || highest_perf >= nominal_perf > lowest_nonlinear_perf > lowest_perf > 0. | + +---------+--------------------------------+------------------------------------------------------------------------------------+ + | 4 | amd_pstate_ut_check_freq || Check if the each frequency values and max freq when set support boost mode | + | | | are reasonable. | + | | || max_freq >= nominal_freq > lowest_nonlinear_freq > min_freq > 0 | + | | || If boost is not active but supported, this maximum frequency will be larger than | + | | | the one in ``cpuinfo``. | + +---------+--------------------------------+------------------------------------------------------------------------------------+ + + 2). Tbench test + + Test and monitor the cpu changes when running tbench benchmark under the specified governor. + These changes include desire performance, frequency, load, performance, energy etc. + The specified governor is ondemand or schedutil. + Tbench can also be tested on the ``acpi-cpufreq`` kernel driver for comparison. + + 3). Gitsource test + + Test and monitor the cpu changes when running gitsource benchmark under the specified governor. + These changes include desire performance, frequency, load, time, energy etc. + The specified governor is ondemand or schedutil. + Gitsource can also be tested on the ``acpi-cpufreq`` kernel driver for comparison. + +#. How to execute the tests + + We use test module in the kselftest frameworks to implement it. + We create ``amd-pstate-ut`` module and tie it into kselftest.(for + details refer to Linux Kernel Selftests [4]_). + + 1). Build + + + open the :c:macro:`CONFIG_X86_AMD_PSTATE` configuration option. + + set the :c:macro:`CONFIG_X86_AMD_PSTATE_UT` configuration option to M. + + make project + + make selftest :: + + $ cd linux + $ make -C tools/testing/selftests + + + make perf :: + + $ cd tools/perf/ + $ make + + + 2). Installation & Steps :: + + $ make -C tools/testing/selftests install INSTALL_PATH=~/kselftest + $ cp tools/perf/perf /usr/bin/perf + $ sudo ./kselftest/run_kselftest.sh -c amd-pstate + + 3). Specified test case :: + + $ cd ~/kselftest/amd-pstate + $ sudo ./run.sh -t basic + $ sudo ./run.sh -t tbench + $ sudo ./run.sh -t tbench -m acpi-cpufreq + $ sudo ./run.sh -t gitsource + $ sudo ./run.sh -t gitsource -m acpi-cpufreq + $ ./run.sh --help + ./run.sh: illegal option -- - + Usage: ./run.sh [OPTION...] + [-h <help>] + [-o <output-file-for-dump>] + [-c <all: All testing, + basic: Basic testing, + tbench: Tbench testing, + gitsource: Gitsource testing.>] + [-t <tbench time limit>] + [-p <tbench process number>] + [-l <loop times for tbench>] + [-i <amd tracer interval>] + [-m <comparative test: acpi-cpufreq>] + + + 4). Results + + + basic + + When you finish test, you will get the following log info :: + + $ dmesg | grep "amd_pstate_ut" | tee log.txt + [12977.570663] amd_pstate_ut: 1 amd_pstate_ut_acpi_cpc_valid success! + [12977.570673] amd_pstate_ut: 2 amd_pstate_ut_check_enabled success! + [12977.571207] amd_pstate_ut: 3 amd_pstate_ut_check_perf success! + [12977.571212] amd_pstate_ut: 4 amd_pstate_ut_check_freq success! + + + tbench + + When you finish test, you will get selftest.tbench.csv and png images. + The selftest.tbench.csv file contains the raw data and the drop of the comparative test. + The png images shows the performance, energy and performan per watt of each test. + Open selftest.tbench.csv : + + +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+ + + Governor | Round | Des-perf | Freq | Load | Performance | Energy | Performance Per Watt | + +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+ + + Unit | | | GHz | | MB/s | J | MB/J | + +=================================================+==============+==========+=========+==========+=============+=========+======================+ + + amd-pstate-ondemand | 1 | | | | 2504.05 | 1563.67 | 158.5378 | + +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+ + + amd-pstate-ondemand | 2 | | | | 2243.64 | 1430.32 | 155.2941 | + +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+ + + amd-pstate-ondemand | 3 | | | | 2183.88 | 1401.32 | 154.2860 | + +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+ + + amd-pstate-ondemand | Average | | | | 2310.52 | 1465.1 | 156.1268 | + +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+ + + amd-pstate-schedutil | 1 | 165.329 | 1.62257 | 99.798 | 2136.54 | 1395.26 | 151.5971 | + +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+ + + amd-pstate-schedutil | 2 | 166 | 1.49761 | 99.9993 | 2100.56 | 1380.5 | 150.6377 | + +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+ + + amd-pstate-schedutil | 3 | 166 | 1.47806 | 99.9993 | 2084.12 | 1375.76 | 149.9737 | + +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+ + + amd-pstate-schedutil | Average | 165.776 | 1.53275 | 99.9322 | 2107.07 | 1383.84 | 150.7399 | + +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+ + + acpi-cpufreq-ondemand | 1 | | | | 2529.9 | 1564.4 | 160.0997 | + +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+ + + acpi-cpufreq-ondemand | 2 | | | | 2249.76 | 1432.97 | 155.4297 | + +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+ + + acpi-cpufreq-ondemand | 3 | | | | 2181.46 | 1406.88 | 153.5060 | + +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+ + + acpi-cpufreq-ondemand | Average | | | | 2320.37 | 1468.08 | 156.4741 | + +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+ + + acpi-cpufreq-schedutil | 1 | | | | 2137.64 | 1385.24 | 152.7723 | + +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+ + + acpi-cpufreq-schedutil | 2 | | | | 2107.05 | 1372.23 | 152.0138 | + +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+ + + acpi-cpufreq-schedutil | 3 | | | | 2085.86 | 1365.35 | 151.2433 | + +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+ + + acpi-cpufreq-schedutil | Average | | | | 2110.18 | 1374.27 | 152.0136 | + +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+ + + acpi-cpufreq-ondemand VS acpi-cpufreq-schedutil | Comprison(%) | | | | -9.0584 | -6.3899 | -2.8506 | + +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+ + + amd-pstate-ondemand VS amd-pstate-schedutil | Comprison(%) | | | | 8.8053 | -5.5463 | -3.4503 | + +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+ + + acpi-cpufreq-ondemand VS amd-pstate-ondemand | Comprison(%) | | | | -0.4245 | -0.2029 | -0.2219 | + +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+ + + acpi-cpufreq-schedutil VS amd-pstate-schedutil | Comprison(%) | | | | -0.1473 | 0.6963 | -0.8378 | + +-------------------------------------------------+--------------+----------+---------+----------+-------------+---------+----------------------+ + + + gitsource + + When you finish test, you will get selftest.gitsource.csv and png images. + The selftest.gitsource.csv file contains the raw data and the drop of the comparative test. + The png images shows the performance, energy and performan per watt of each test. + Open selftest.gitsource.csv : + + +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+ + + Governor | Round | Des-perf | Freq | Load | Time | Energy | Performance Per Watt | + +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+ + + Unit | | | GHz | | s | J | 1/J | + +=================================================+==============+==========+==========+==========+=============+=========+======================+ + + amd-pstate-ondemand | 1 | 50.119 | 2.10509 | 23.3076 | 475.69 | 865.78 | 0.001155027 | + +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+ + + amd-pstate-ondemand | 2 | 94.8006 | 1.98771 | 56.6533 | 467.1 | 839.67 | 0.001190944 | + +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+ + + amd-pstate-ondemand | 3 | 76.6091 | 2.53251 | 43.7791 | 467.69 | 855.85 | 0.001168429 | + +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+ + + amd-pstate-ondemand | Average | 73.8429 | 2.20844 | 41.2467 | 470.16 | 853.767 | 0.001171279 | + +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+ + + amd-pstate-schedutil | 1 | 165.919 | 1.62319 | 98.3868 | 464.17 | 866.8 | 0.001153668 | + +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+ + + amd-pstate-schedutil | 2 | 165.97 | 1.31309 | 99.5712 | 480.15 | 880.4 | 0.001135847 | + +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+ + + amd-pstate-schedutil | 3 | 165.973 | 1.28448 | 99.9252 | 481.79 | 867.02 | 0.001153375 | + +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+ + + amd-pstate-schedutil | Average | 165.954 | 1.40692 | 99.2944 | 475.37 | 871.407 | 0.001147569 | + +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+ + + acpi-cpufreq-ondemand | 1 | | | | 2379.62 | 742.96 | 0.001345967 | + +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+ + + acpi-cpufreq-ondemand | 2 | | | | 441.74 | 817.49 | 0.001223256 | + +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+ + + acpi-cpufreq-ondemand | 3 | | | | 455.48 | 820.01 | 0.001219497 | + +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+ + + acpi-cpufreq-ondemand | Average | | | | 425.613 | 793.487 | 0.001260260 | + +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+ + + acpi-cpufreq-schedutil | 1 | | | | 459.69 | 838.54 | 0.001192548 | + +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+ + + acpi-cpufreq-schedutil | 2 | | | | 466.55 | 830.89 | 0.001203528 | + +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+ + + acpi-cpufreq-schedutil | 3 | | | | 470.38 | 837.32 | 0.001194286 | + +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+ + + acpi-cpufreq-schedutil | Average | | | | 465.54 | 835.583 | 0.001196769 | + +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+ + + acpi-cpufreq-ondemand VS acpi-cpufreq-schedutil | Comprison(%) | | | | 9.3810 | 5.3051 | -5.0379 | + +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+ + + amd-pstate-ondemand VS amd-pstate-schedutil | Comprison(%) | 124.7392 | -36.2934 | 140.7329 | 1.1081 | 2.0661 | -2.0242 | + +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+ + + acpi-cpufreq-ondemand VS amd-pstate-ondemand | Comprison(%) | | | | 10.4665 | 7.5968 | -7.0605 | + +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+ + + acpi-cpufreq-schedutil VS amd-pstate-schedutil | Comprison(%) | | | | 2.1115 | 4.2873 | -4.1110 | + +-------------------------------------------------+--------------+----------+----------+----------+-------------+---------+----------------------+ Reference =========== @@ -405,3 +770,6 @@ Reference .. [3] Processor Programming Reference (PPR) for AMD Family 19h Model 51h, Revision A1 Processors https://www.amd.com/system/files/TechDocs/56569-A1-PUB.zip + +.. [4] Linux Kernel Selftests, + https://www.kernel.org/doc/html/latest/dev-tools/kselftest.html |