linux-kernel - RE: [PATCH v4 11/11] cpufreq: amd-pstate: enable shared memory type CPPC by default

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Date: Wed, 19 Jun 2024 03:06:22 +0000
From: "Yuan, Perry" <Perry.Yuan@....com>
To: "Limonciello, Mario" <Mario.Limonciello@....com>,
	"rafael.j.wysocki@...el.com" <rafael.j.wysocki@...el.com>,
	"viresh.kumar@...aro.org" <viresh.kumar@...aro.org>, "Huang, Ray"
	<Ray.Huang@....com>, "Shenoy, Gautham Ranjal" <gautham.shenoy@....com>,
	"Petkov, Borislav" <Borislav.Petkov@....com>
CC: "Deucher, Alexander" <Alexander.Deucher@....com>, "Huang, Shimmer"
	<Shimmer.Huang@....com>, "Du, Xiaojian" <Xiaojian.Du@....com>, "Meng, Li
 (Jassmine)" <Li.Meng@....com>, "linux-pm@...r.kernel.org"
	<linux-pm@...r.kernel.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v4 11/11] cpufreq: amd-pstate: enable shared memory type
 CPPC by default

[AMD Official Use Only - AMD Internal Distribution Only]

> -----Original Message-----
> From: Limonciello, Mario <Mario.Limonciello@....com>
> Sent: Wednesday, June 19, 2024 3:25 AM
> To: Yuan, Perry <Perry.Yuan@....com>; rafael.j.wysocki@...el.com;
> viresh.kumar@...aro.org; Huang, Ray <Ray.Huang@....com>; Shenoy,
> Gautham Ranjal <gautham.shenoy@....com>; Petkov, Borislav
> <Borislav.Petkov@....com>
> Cc: Deucher, Alexander <Alexander.Deucher@....com>; Huang, Shimmer
> <Shimmer.Huang@....com>; Du, Xiaojian <Xiaojian.Du@....com>; Meng,
> Li (Jassmine) <Li.Meng@....com>; linux-pm@...r.kernel.org; linux-
> kernel@...r.kernel.org
> Subject: Re: [PATCH v4 11/11] cpufreq: amd-pstate: enable shared memory
> type CPPC by default
>
> On 6/17/2024 01:59, Perry Yuan wrote:
> > The amd-pstate-epp driver has been implemented and resolves the
> > performance drop issue seen in passive mode. Users who enable the
> > active mode driver will not experience a performance drop compared to
> > the passive mode driver. Therefore, the EPP driver should be loaded by
> > default at system boot.
>
> I think this commit message should specifically reference that it's being
> enabled by default on shared memory designs as that's the net new.
>
> The code change looks good, go ahead and add
>
> Reviewed-by: Mario Limonciello <mario.limonciello@....com>
>
> on the next version as long as you've added a sentence about shared
> memory designs to commit message.

Thanks for the review, will add the shared memory systems words to commit log in the next version.

>
> >
> > Signed-off-by: Perry Yuan <perry.yuan@....com>
> > ---
> >   drivers/cpufreq/amd-pstate.c | 13 +------------
> >   1 file changed, 1 insertion(+), 12 deletions(-)
> >
> > diff --git a/drivers/cpufreq/amd-pstate.c
> > b/drivers/cpufreq/amd-pstate.c index b48fd60cbc6d..eca2f7dcf7ce 100644
> > --- a/drivers/cpufreq/amd-pstate.c
> > +++ b/drivers/cpufreq/amd-pstate.c
> > @@ -96,15 +96,6 @@ enum amd_core_type {
> >     CPU_CORE_TYPE_UNDEFINED = 2,
> >   };
> >
> > -/*
> > - * TODO: We need more time to fine tune processors with shared memory
> > solution
> > - * with community together.
> > - *
> > - * There are some performance drops on the CPU benchmarks which
> > reports from
> > - * Suse. We are co-working with them to fine tune the shared memory
> > solution. So
> > - * we disable it by default to go acpi-cpufreq on these processors
> > and add a
> > - * module parameter to be able to enable it manually for debugging.
> > - */
> >   static struct cpufreq_driver *current_pstate_driver;
> >   static struct cpufreq_driver amd_pstate_driver;
> >   static struct cpufreq_driver amd_pstate_epp_driver; @@ -1867,11
> > +1858,9 @@ static int __init amd_pstate_init(void)
> >             /* Disable on the following configs by default:
> >              * 1. Undefined platforms
> >              * 2. Server platforms
> > -            * 3. Shared memory designs
> >              */
> >             if (amd_pstate_acpi_pm_profile_undefined() ||
> > -               amd_pstate_acpi_pm_profile_server() ||
> > -               !cpu_feature_enabled(X86_FEATURE_CPPC)) {
> > +               amd_pstate_acpi_pm_profile_server()) {
> >                     pr_info("driver load is disabled, boot with specific
> mode to enable this\n");
> >                     return -ENODEV;
> >             }