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Date: Tue, 31 Jan 2023 17:45:00 +0000
From: Wyes Karny <wyes.karny@....com>
To: Mario Limonciello <mario.limonciello@....com>
Cc: Rafael J Wysocki <rafael@...nel.org>,
Huang Rui <ray.huang@....com>,
Jonathan Corbet <corbet@....net>,
Viresh Kumar <viresh.kumar@...aro.org>, Perry.Yuan@....com,
linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-pm@...r.kernel.org, Bagas Sanjaya <bagasdotme@...il.com>,
santosh.shukla@....com, Len Brown <lenb@...nel.org>,
Robert Moore <robert.moore@...el.com>,
Borislav Petkov <bp@...en8.de>,
Ananth Narayan <ananth.narayan@....com>,
gautham.shenoy@....com, Tor Vic <torvic9@...lbox.org>
Subject: Re: [PATCH v4 3/6] cpufreq: amd_pstate: Add guided autonomous mode
On 31 Jan 07:37, Mario Limonciello wrote:
> On 1/30/23 23:21, Wyes Karny wrote:
> > From ACPI spec below 3 modes for CPPC can be defined:
> > 1. Non autonomous: OS scaling governor specifies operating frequency/
> > performance level through `Desired Performance` register and platform
> > follows that.
> > 2. Guided autonomous: OS scaling governor specifies min and max
> > frequencies/ performance levels through `Minimum Performance` and
> > `Maximum Performance` register, and platform can autonomously select an
> > operating frequency in this range.
> > 3. Fully autonomous: OS only hints (via EPP) to platform for the required
> > energy performance preference for the workload and platform autonomously
> > scales the frequency.
> >
> > Currently (1) is supported by amd_pstate as passive mode, and (3) is
> > implemented by EPP support. This change is to support (2).
> >
> > In guided autonomous mode the min_perf is based on the input from the
> > scaling governor. For example, in case of schedutil this value depends
> > on the current utilization. And max_perf is set to max capacity.
> >
> > To activate guided auto mode ``amd_pstate=guided`` command line
> > parameter has to be passed in the kernel.
> >
> > Signed-off-by: Wyes Karny <wyes.karny@....com>
> > ---
> > .../admin-guide/kernel-parameters.txt | 15 +++++---
> > drivers/cpufreq/amd-pstate.c | 34 +++++++++++++++----
> > include/linux/amd-pstate.h | 2 ++
> > 3 files changed, 40 insertions(+), 11 deletions(-)
> >
> > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> > index e3618dfdb36a..0d8486325c9a 100644
> > --- a/Documentation/admin-guide/kernel-parameters.txt
> > +++ b/Documentation/admin-guide/kernel-parameters.txt
> > @@ -7015,11 +7015,11 @@
> > 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.)
> > + Use amd_pstate with passive mode as a scaling driver.
> > + In this mode autonomous selection is disabled.
> > + Driver requests a desired performance level and platform
> > + tires to match the same performance level (if it is
>
> s/tires/tries/
>
> I don't think you need the () either in this sentence.
>
> > + satisfied by guaranteed performance level).
> > active
> > Use amd_pstate_epp driver instance as the scaling driver,
> > driver provides a hint to the hardware if software wants
> > @@ -7027,3 +7027,8 @@
> > to the CPPC firmware. then CPPC power algorithm will
> > calculate the runtime workload and adjust the realtime cores
> > frequency.
> > + guided
> > + Activate guided autonomous mode. Driver requests minimum and
> > + maximum performance level and the platform autonomously
> > + selects a performance level in this range and appropriate
> > + to the current workload.
> > diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> > index c5731fefcbef..48ab4684c3a5 100644
> > --- a/drivers/cpufreq/amd-pstate.c
> > +++ b/drivers/cpufreq/amd-pstate.c
> > @@ -267,7 +267,22 @@ static int cppc_init_perf(struct amd_cpudata *cpudata)
> > cppc_perf.lowest_nonlinear_perf);
> > WRITE_ONCE(cpudata->lowest_perf, cppc_perf.lowest_perf);
> > - return 0;
> > + if (cppc_state == AMD_PSTATE_ACTIVE)
> > + return 0;
> > +
> > + ret = cppc_get_auto_sel_caps(cpudata->cpu, &cppc_perf);
> > + if (ret) {
> > + pr_warn("failed to get auto_sel, ret: %d\n", ret);
> > + return 0;
> > + }
> > +
> > + ret = cppc_set_auto_sel(cpudata->cpu,
> > + (cppc_state == AMD_PSTATE_PASSIVE) ? 0 : 1);
> > +
> > + if (ret)
> > + pr_warn("failed to set auto_sel, ret: %d\n", ret);
> > +
> > + return ret;
> > }
> > DEFINE_STATIC_CALL(amd_pstate_init_perf, pstate_init_perf);
> > @@ -344,12 +359,18 @@ static inline bool amd_pstate_sample(struct amd_cpudata *cpudata)
> > }
> > static void amd_pstate_update(struct amd_cpudata *cpudata, u32 min_perf,
> > - u32 des_perf, u32 max_perf, bool fast_switch)
> > + u32 des_perf, u32 max_perf, bool fast_switch, int guv_flags)
>
> You meant "gov_flags" not "guv_flags" right?
>
> > {
> > u64 prev = READ_ONCE(cpudata->cppc_req_cached);
> > u64 value = prev;
> > des_perf = clamp_t(unsigned long, des_perf, min_perf, max_perf);
> > +
> > + if ((cppc_state == AMD_PSTATE_GUIDED) && (guv_flags & CPUFREQ_GOV_DYNAMIC_SWITCHING)) {
> > + min_perf = des_perf;
> > + des_perf = 0;
> > + }
> > +
> > value &= ~AMD_CPPC_MIN_PERF(~0L);
> > value |= AMD_CPPC_MIN_PERF(min_perf);
> > @@ -404,7 +425,7 @@ static int amd_pstate_target(struct cpufreq_policy *policy,
> > cpufreq_freq_transition_begin(policy, &freqs);
> > amd_pstate_update(cpudata, min_perf, des_perf,
> > - max_perf, false);
> > + max_perf, false, policy->governor->flags);
> > cpufreq_freq_transition_end(policy, &freqs, false);
> > return 0;
> > @@ -438,7 +459,8 @@ static void amd_pstate_adjust_perf(unsigned int cpu,
> > if (max_perf < min_perf)
> > max_perf = min_perf;
> > - amd_pstate_update(cpudata, min_perf, des_perf, max_perf, true);
> > + amd_pstate_update(cpudata, min_perf, des_perf, max_perf, true,
> > + policy->governor->flags);
> > cpufreq_cpu_put(policy);
> > }
> > @@ -1238,7 +1260,7 @@ static int __init amd_pstate_init(void)
> > /* capability check */
> > if (boot_cpu_has(X86_FEATURE_CPPC)) {
> > pr_debug("AMD CPPC MSR based functionality is supported\n");
> > - if (cppc_state == AMD_PSTATE_PASSIVE)
> > + if (cppc_state != AMD_PSTATE_ACTIVE)
> > current_pstate_driver->adjust_perf = amd_pstate_adjust_perf;
> > } else {
> > pr_debug("AMD CPPC shared memory based functionality is supported\n");
> > @@ -1300,7 +1322,7 @@ static int __init amd_pstate_param(char *str)
> > if (cppc_state == AMD_PSTATE_ACTIVE)
> > current_pstate_driver = &amd_pstate_epp_driver;
> > - if (cppc_state == AMD_PSTATE_PASSIVE)
> > + if (cppc_state == AMD_PSTATE_PASSIVE || cppc_state == AMD_PSTATE_GUIDED)
> > current_pstate_driver = &amd_pstate_driver;
> > return 0;
> > diff --git a/include/linux/amd-pstate.h b/include/linux/amd-pstate.h
> > index e9e291b7c2f9..85e980b8e0ac 100644
> > --- a/include/linux/amd-pstate.h
> > +++ b/include/linux/amd-pstate.h
> > @@ -92,6 +92,7 @@ enum amd_pstate_mode {
> > AMD_PSTATE_DISABLE = 0,
> > AMD_PSTATE_PASSIVE,
> > AMD_PSTATE_ACTIVE,
> > + AMD_PSTATE_GUIDED,
> > AMD_PSTATE_MAX,
> > };
> > @@ -99,6 +100,7 @@ static const char * const amd_pstate_mode_string[] = {
> > [AMD_PSTATE_DISABLE] = "disable",
> > [AMD_PSTATE_PASSIVE] = "passive",
> > [AMD_PSTATE_ACTIVE] = "active",
> > + [AMD_PSTATE_GUIDED] = "guided",
> > NULL,
> > };
>
> With two nits fixed
>
> Reviewed-by: Mario Limonciello <mario.limonciello@....com>
Thanks! I'll fix those.
>
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