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authorLinus Torvalds <torvalds@linux-foundation.org>2022-11-25 23:43:33 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2022-11-25 23:43:33 +0300
commit88817acb8b75fe533fb5dfb6234a4e2104465e53 (patch)
tree7ec2051a9889a077d069c0527a53aa0d6ab66ce6 /Documentation
parente3ebac80b6e9efe47b0ac3bf4b2d800b0b1958ff (diff)
parent1056d314709d0607a22e589c54b1e47e0da57b9d (diff)
downloadlinux-88817acb8b75fe533fb5dfb6234a4e2104465e53.tar.xz
Merge tag 'pm-6.1-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull power management fixes from Rafael Wysocki: "These revert a recent change in the schedutil cpufreq governor that had not been expected to make any functional difference, but turned out to introduce a performance regression, fix an initialization issue in the amd-pstate driver and make it actually replace the venerable ACPI cpufreq driver on the supported systems by default. Specifics: - Revert a recent schedutil cpufreq governor change that introduced a performace regression on Pixel 6 (Sam Wu) - Fix amd-pstate driver initialization after running the kernel via kexec (Wyes Karny) - Turn amd-pstate into a built-in driver which allows it to take precedence over acpi-cpufreq by default on supported systems and amend it with a mechanism to disable this behavior (Perry Yuan) - Update amd-pstate documentation in accordance with the other changes made to it (Perry Yuan)" * tag 'pm-6.1-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: Documentation: add amd-pstate kernel command line options Documentation: amd-pstate: add driver working mode introduction cpufreq: amd-pstate: add amd-pstate driver parameter for mode selection cpufreq: amd-pstate: change amd-pstate driver to be built-in type cpufreq: amd-pstate: cpufreq: amd-pstate: reset MSR_AMD_PERF_CTL register at init Revert "cpufreq: schedutil: Move max CPU capacity to sugov_policy"
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/admin-guide/kernel-parameters.txt11
-rw-r--r--Documentation/admin-guide/pm/amd-pstate.rst30
2 files changed, 24 insertions, 17 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index a465d5242774..42af9ca0127e 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -6959,3 +6959,14 @@
memory, and other data can't be written using
xmon commands.
off xmon is disabled.
+
+ amd_pstate= [X86]
+ disable
+ Do not enable amd_pstate as the default
+ scaling driver for the supported processors
+ passive
+ Use amd_pstate as a scaling driver, driver requests a
+ desired performance on this abstract scale and the power
+ management firmware translates the requests into actual
+ hardware states (core frequency, data fabric and memory
+ clocks etc.)
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
-<perf_cap_>`_, 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 <perf_cap_>`_
-or `Shared Memory Support <perf_cap_>`_ : ::
-
- 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
-<perf_cap_>`_. Otherwise, it supports `Shared Memory Support <perf_cap_>`_.
+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``