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

Yuan, Perry
2024-06-19T03:06:24Z

[AMD Official Use Only - AMD Internal Distribution Only]

> -----Original Message-----
> From: Limonciello, Mario <Mario.Limonciello@amd.com>
> Sent: Wednesday, June 19, 2024 3:25 AM
> To: Yuan, Perry <Perry.Yuan@amd.com>; rafael.j.wysocki@intel.com;
> viresh.kumar@linaro.org; Huang, Ray <Ray.Huang@amd.com>; Shenoy,
> Gautham Ranjal <gautham.shenoy@amd.com>; Petkov, Borislav
> <Borislav.Petkov@amd.com>
> Cc: Deucher, Alexander <Alexander.Deucher@amd.com>; Huang, Shimmer
> <Shimmer.Huang@amd.com>; Du, Xiaojian <Xiaojian.Du@amd.com>; Meng,
> Li (Jassmine) <Li.Meng@amd.com>; linux-pm@vger.kernel.org; linux-
> kernel@vger.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@amd.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@amd.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;
> > }