From: "Yuan, Perry" <Perry.Yuan@amd.com>
To: Punit Agrawal <punit.agrawal@bytedance.com>
Cc: "rafael.j.wysocki@intel.com" <rafael.j.wysocki@intel.com>,
"Huang, Ray" <Ray.Huang@amd.com>,
"viresh.kumar@linaro.org" <viresh.kumar@linaro.org>,
"Sharma, Deepak" <Deepak.Sharma@amd.com>,
"Limonciello, Mario" <Mario.Limonciello@amd.com>,
"Fontenot, Nathan" <Nathan.Fontenot@amd.com>,
"Deucher, Alexander" <Alexander.Deucher@amd.com>,
"Su, Jinzhou (Joe)" <Jinzhou.Su@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-pm@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH v5 6/7] cpufreq: amd-pstate: update pstate frequency transition delay time
Date: Tue, 16 Aug 2022 07:02:27 +0000 [thread overview]
Message-ID: <DM4PR12MB5278E6B6EC656747AE67BFAF9C6B9@DM4PR12MB5278.namprd12.prod.outlook.com> (raw)
In-Reply-To: <87bkslim2c.fsf@stealth>
[AMD Official Use Only - General]
Hi Punit
> -----Original Message-----
> From: Punit Agrawal <punit.agrawal@bytedance.com>
> Sent: Monday, August 15, 2022 11:06 PM
> To: Yuan, Perry <Perry.Yuan@amd.com>
> Cc: rafael.j.wysocki@intel.com; Huang, Ray <Ray.Huang@amd.com>;
> viresh.kumar@linaro.org; Sharma, Deepak <Deepak.Sharma@amd.com>;
> Limonciello, Mario <Mario.Limonciello@amd.com>; Fontenot, Nathan
> <Nathan.Fontenot@amd.com>; Deucher, Alexander
> <Alexander.Deucher@amd.com>; Su, Jinzhou (Joe) <Jinzhou.Su@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 v5 6/7] cpufreq: amd-pstate: update pstate frequency
> transition delay time
>
> [CAUTION: External Email]
>
> Perry Yuan <Perry.Yuan@amd.com> writes:
>
> > Change the default transition latency to be 20ms that is more
> > reasonable transition delay for AMD processors in non-EPP driver mode.
> >
> > Update transition delay time to 1ms, in the AMD CPU autonomous mode
> > and non-autonomous mode, CPPC firmware will decide frequency at 1ms
> > timescale based on the workload utilization.
> >
> > Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
> > Signed-off-by: Perry Yuan <Perry.Yuan@amd.com>
> > ---
> > drivers/cpufreq/amd-pstate.c | 4 ++--
> > 1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/cpufreq/amd-pstate.c
> > b/drivers/cpufreq/amd-pstate.c index e40177d14310..9cb051d61422 100644
> > --- a/drivers/cpufreq/amd-pstate.c
> > +++ b/drivers/cpufreq/amd-pstate.c
> > @@ -41,8 +41,8 @@
> > #include <asm/msr.h>
> > #include "amd-pstate-trace.h"
> >
> > -#define AMD_PSTATE_TRANSITION_LATENCY 0x20000
> > -#define AMD_PSTATE_TRANSITION_DELAY 500
> > +#define AMD_PSTATE_TRANSITION_LATENCY 20000
> > +#define AMD_PSTATE_TRANSITION_DELAY 1000
>
> How were these values derived? If from documentation, it'll be good to add a
> link to the relevant documentation. And if they were derived from testing,
> please mention this in the commit log (along with some details of the tests used
> to determine the value).
The values are calculated from the CPU PM firmware and hardware design.
There are some latency and delay values defined in the PM firmware, I have no documents about the detail for now.
Perry.
>
> >
> > /*
> > * TODO: We need more time to fine tune processors with shared memory
> > solution
next prev parent reply other threads:[~2022-08-16 8:56 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-14 16:35 [PATCH v5 0/7] AMD Pstate Enhancement And Issue Fixs Perry Yuan
2022-08-14 16:35 ` [PATCH v5 1/7] cpufreq: amd-pstate: cleanup the unused and duplicated headers declaration Perry Yuan
2022-08-15 15:04 ` Punit Agrawal
2022-09-01 5:34 ` Yuan, Perry
2022-08-14 16:35 ` [PATCH v5 2/7] cpufreq: amd-pstate: simplify cpudata pointer assignment Perry Yuan
2022-08-14 16:35 ` [PATCH v5 3/7] cpufreq: amd-pstate: fix white-space Perry Yuan
2022-08-31 19:07 ` Rafael J. Wysocki
2022-08-14 16:35 ` [PATCH v5 4/7] cpufreq: amd_pstate: fix wrong lowest perf fetch Perry Yuan
2022-08-15 15:05 ` Punit Agrawal
2022-08-31 8:53 ` Yuan, Perry
2022-09-01 14:58 ` Punit Agrawal
2022-08-14 16:35 ` [PATCH v5 5/7] cpufreq: amd_pstate: map desired perf into pstate scope for powersave governor Perry Yuan
2022-08-14 16:35 ` [PATCH v5 6/7] cpufreq: amd-pstate: update pstate frequency transition delay time Perry Yuan
2022-08-15 15:05 ` Punit Agrawal
2022-08-16 7:02 ` Yuan, Perry [this message]
2022-08-16 16:03 ` Punit Agrawal
2022-08-14 16:35 ` [PATCH v5 7/7] cpufreq: amd-pstate: add ACPI disabled check in acpi_cpc_valid() Perry Yuan
2022-08-25 11:56 ` Rafael J. Wysocki
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