From 8a2cbf72a43ade1ed00760f65914e322599fe662 Mon Sep 17 00:00:00 2001 From: Perry Yuan Date: Thu, 17 Nov 2022 15:35:40 +0800 Subject: Documentation: amd-pstate: add driver working mode introduction Introduce the `amd_pstate` driver new working mode with `amd_pstate=passive` added to kernel command line. If there is no passive mode enabled by user, amd_pstate driver will be disabled by default for now. Acked-by: Huang Rui Reviewed-by: Gautham R. Shenoy Tested-by: Wyes Karny Signed-off-by: Perry Yuan Signed-off-by: Rafael J. Wysocki --- Documentation/admin-guide/pm/amd-pstate.rst | 30 +++++++++++++---------------- 1 file changed, 13 insertions(+), 17 deletions(-) diff --git a/Documentation/admin-guide/pm/amd-pstate.rst b/Documentation/admin-guide/pm/amd-pstate.rst index 8f3d30c5a0d8..06e23538f79c 100644 --- a/Documentation/admin-guide/pm/amd-pstate.rst +++ b/Documentation/admin-guide/pm/amd-pstate.rst @@ -283,23 +283,19 @@ efficiency frequency management method on AMD processors. Kernel Module Options for ``amd-pstate`` ========================================= -.. _shared_mem: - -``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 -`_, we disable it presently and will re-enable this by default -once we address performance issue with this solution. - -To check whether the current processor is using `Full MSR Support `_ -or `Shared Memory Support `_ : :: - - 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 - -If the CPU flags have ``cppc``, then this processor supports `Full MSR Support -`_. Otherwise, it supports `Shared Memory Support `_. +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. ``cpupower`` tool support for ``amd-pstate`` -- cgit v1.2.3