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Date: Fri, 17 Dec 2021 15:37:43 +0800
From: Huang Rui <ray.huang@....com>
To: "Rafael J. Wysocki" <rafael@...nel.org>
Cc: "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
Viresh Kumar <viresh.kumar@...aro.org>,
Shuah Khan <skhan@...uxfoundation.org>,
Borislav Petkov <bp@...e.de>,
Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...nel.org>,
Giovanni Gherdovich <ggherdovich@...e.cz>,
Linux PM <linux-pm@...r.kernel.org>,
"Sharma, Deepak" <Deepak.Sharma@....com>,
"Deucher, Alexander" <Alexander.Deucher@....com>,
"Limonciello, Mario" <Mario.Limonciello@....com>,
Steven Noonan <steven@...vesoftware.com>,
"Fontenot, Nathan" <Nathan.Fontenot@....com>,
"Su, Jinzhou (Joe)" <Jinzhou.Su@....com>,
"Du, Xiaojian" <Xiaojian.Du@....com>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
the arch/x86 maintainers <x86@...nel.org>
Subject: Re: [PATCH v5 08/22] cpufreq: amd: introduce the support for the
processors with shared memory solution
On Fri, Dec 17, 2021 at 02:04:11AM +0800, Rafael J. Wysocki wrote:
> On Tue, Nov 30, 2021 at 1:38 PM Huang Rui <ray.huang@....com> wrote:
> >
> > In some of Zen2 and Zen3 based processors, they are using the shared
> > memory that exposed from ACPI SBIOS. In this kind of the processors,
> > there is no MSR support, so we add acpi cppc function as the backend for
> > them.
> >
> > It is using a module param (shared_mem) to enable related processors
> > manually. We will enable this by default once we address performance
> > issue on this solution.
> >
> > Signed-off-by: Jinzhou Su <Jinzhou.Su@....com>
> > Signed-off-by: Huang Rui <ray.huang@....com>
> > ---
> > drivers/cpufreq/amd-pstate.c | 72 ++++++++++++++++++++++++++++++++++--
> > 1 file changed, 68 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> > index cab266b8bf35..68991c450fd5 100644
> > --- a/drivers/cpufreq/amd-pstate.c
> > +++ b/drivers/cpufreq/amd-pstate.c
> > @@ -35,6 +35,19 @@
> > #define AMD_PSTATE_TRANSITION_LATENCY 0x20000
> > #define AMD_PSTATE_TRANSITION_DELAY 500
> >
> > +/* 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 bool shared_mem = false;
> > +module_param(shared_mem, bool, 0444);
> > +MODULE_PARM_DESC(shared_mem,
> > + "enable amd-pstate on processors with shared memory solution (false = disabled (default), true = enabled)");
> > +
> > static struct cpufreq_driver amd_pstate_driver;
> >
> > struct amd_cpudata {
> > @@ -60,6 +73,19 @@ static inline int pstate_enable(bool enable)
> > return wrmsrl_safe(MSR_AMD_CPPC_ENABLE, enable);
> > }
> >
> > +static int cppc_enable(bool enable)
> > +{
> > + int cpu, ret = 0;
> > +
> > + for_each_online_cpu(cpu) {
> > + ret = cppc_set_enable(cpu, enable);
> > + if (ret)
> > + return ret;
> > + }
> > +
> > + return ret;
> > +}
> > +
> > DEFINE_STATIC_CALL(amd_pstate_enable, pstate_enable);
> >
> > static inline int amd_pstate_enable(bool enable)
> > @@ -90,6 +116,24 @@ static int pstate_init_perf(struct amd_cpudata *cpudata)
> > return 0;
> > }
> >
> > +static int cppc_init_perf(struct amd_cpudata *cpudata)
> > +{
> > + struct cppc_perf_caps cppc_perf;
> > +
> > + int ret = cppc_get_perf_caps(cpudata->cpu, &cppc_perf);
> > + if (ret)
> > + return ret;
> > +
> > + WRITE_ONCE(cpudata->highest_perf, amd_get_highest_perf());
> > +
> > + WRITE_ONCE(cpudata->nominal_perf, cppc_perf.nominal_perf);
> > + WRITE_ONCE(cpudata->lowest_nonlinear_perf,
> > + cppc_perf.lowest_nonlinear_perf);
> > + WRITE_ONCE(cpudata->lowest_perf, cppc_perf.lowest_perf);
> > +
> > + return 0;
> > +}
> > +
> > DEFINE_STATIC_CALL(amd_pstate_init_perf, pstate_init_perf);
> >
> > static inline int amd_pstate_init_perf(struct amd_cpudata *cpudata)
> > @@ -107,6 +151,19 @@ static void pstate_update_perf(struct amd_cpudata *cpudata, u32 min_perf,
> > READ_ONCE(cpudata->cppc_req_cached));
> > }
> >
> > +static void cppc_update_perf(struct amd_cpudata *cpudata,
> > + u32 min_perf, u32 des_perf,
> > + u32 max_perf, bool fast_switch)
> > +{
> > + struct cppc_perf_ctrls perf_ctrls;
> > +
> > + perf_ctrls.max_perf = max_perf;
> > + perf_ctrls.min_perf = min_perf;
> > + perf_ctrls.desired_perf = des_perf;
> > +
> > + cppc_set_perf(cpudata->cpu, &perf_ctrls);
> > +}
> > +
> > DEFINE_STATIC_CALL(amd_pstate_update_perf, pstate_update_perf);
> >
> > static inline void amd_pstate_update_perf(struct amd_cpudata *cpudata,
> > @@ -326,7 +383,8 @@ static int amd_pstate_cpu_init(struct cpufreq_policy *policy)
> > /* It will be updated by governor */
> > policy->cur = policy->cpuinfo.min_freq;
> >
> > - policy->fast_switch_possible = true;
> > + if (boot_cpu_has(X86_FEATURE_CPPC))
> > + policy->fast_switch_possible = true;
> >
> > ret = freq_qos_add_request(&policy->constraints, &cpudata->req[0],
> > FREQ_QOS_MIN, policy->cpuinfo.min_freq);
> > @@ -376,7 +434,6 @@ static struct cpufreq_driver amd_pstate_driver = {
> > .flags = CPUFREQ_CONST_LOOPS | CPUFREQ_NEED_UPDATE_LIMITS,
> > .verify = amd_pstate_verify,
> > .target = amd_pstate_target,
> > - .adjust_perf = amd_pstate_adjust_perf,
> > .init = amd_pstate_cpu_init,
> > .exit = amd_pstate_cpu_exit,
> > .name = "amd-pstate",
> > @@ -399,8 +456,15 @@ static int __init amd_pstate_init(void)
> > return -EEXIST;
> >
> > /* capability check */
> > - if (!boot_cpu_has(X86_FEATURE_CPPC)) {
> > - pr_debug("AMD CPPC MSR based functionality is not supported\n");
> > + if (boot_cpu_has(X86_FEATURE_CPPC)) {
> > + pr_debug("AMD CPPC MSR based functionality is supported\n");
> > + amd_pstate_driver.adjust_perf = amd_pstate_adjust_perf;
> > + } else if (shared_mem) {
> > + static_call_update(amd_pstate_enable, cppc_enable);
> > + static_call_update(amd_pstate_init_perf, cppc_init_perf);
> > + static_call_update(amd_pstate_update_perf, cppc_update_perf);
>
> I would rather add the static call definitions in this patch,
> otherwise is somewhat cumbersome to review the series.
>
I see. Will move them into this patch in V6.
Thanks,
Ray
> > + } else {
> > + pr_info("This processor supports shared memory solution, you can enable it with amd_pstate.shared_mem=1\n");
> > return -ENODEV;
> > }
> >
> > --
> > 2.25.1
> >
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