Messages in this thread | | | From | "Yuan, Perry" <> | Subject | RE: [PATCH 4/5] Documentation: amd-pstate: add driver working mode introduction | Date | Thu, 17 Nov 2022 04:17:50 +0000 |
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[AMD Official Use Only - General]
Hi Gautham
> -----Original Message----- > From: Shenoy, Gautham Ranjal <gautham.shenoy@amd.com> > Sent: Thursday, November 17, 2022 12:16 PM > To: Yuan, Perry <Perry.Yuan@amd.com> > Cc: rafael.j.wysocki@intel.com; Huang, Ray <Ray.Huang@amd.com>; > viresh.kumar@linaro.org; Limonciello, Mario <Mario.Limonciello@amd.com>; > Fontenot, Nathan <Nathan.Fontenot@amd.com>; Deucher, Alexander > <Alexander.Deucher@amd.com>; Sharma, Deepak > <Deepak.Sharma@amd.com>; Huang, Shimmer > <Shimmer.Huang@amd.com>; Meng, Li (Jassmine) <Li.Meng@amd.com>; > Du, Xiaojian <Xiaojian.Du@amd.com>; Karny, Wyes > <Wyes.Karny@amd.com>; Narayan, Ananth <Ananth.Narayan@amd.com>; > linux-pm@vger.kernel.org; linux-kernel@vger.kernel.org > Subject: Re: [PATCH 4/5] Documentation: amd-pstate: add driver working > mode introduction > > Hello Perry, > > On Thu, Nov 17, 2022 at 10:49:54AM +0800, Perry Yuan wrote: > > Introduce the `amd-pstate` driver new working mode with > > `amd-pstate=passive` added to kernel command line. > > It should be `amd_pstate=passive` here to be consistent with the early > parameter and the rest of the documentation.
Thank you help to review, Will fix this with V2
Perry.
> > > > If there is no passive mode enabled by user, amd-pstate driver will be > > disabled by default for now. > > > > Signed-off-by: Perry Yuan <Perry.Yuan@amd.com> > > --- > > 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 -<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. > > Otherwise looks good to me. > > Reviewed-by: Gautham R. Shenoy <gautham.shenoy@amd.com> > > -- > Thanks and Regards > gautham.
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