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Date: Tue, 1 Mar 2022 16:26:16 +0100
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Jinzhou Su <Jinzhou.Su@....com>
Cc: "Rafael J. Wysocki" <rjw@...ysocki.net>,
Linux PM <linux-pm@...r.kernel.org>,
Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
Doug Smythies <dsmythies@...us.net>,
Huang Rui <ray.huang@....com>,
Viresh Kumar <viresh.kumar@...aro.org>,
Todd Brandt <todd.e.brandt@...ux.intel.com>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Deepak Sharma <deepak.sharma@....com>,
Alex Deucher <alexander.deucher@....com>,
"Du, Xiaojian" <xiaojian.du@....com>,
"Yuan, Perry" <perry.yuan@....com>, li.meng@....com
Subject: Re: [PATCH 1/3] cpufreq: amd-pstate: Add more tracepoint for AMD
P-State module
On Wed, Feb 23, 2022 at 11:04 AM Jinzhou Su <Jinzhou.Su@....com> wrote:
>
> Add frequency, mperf, aperf and tsc in the trace. This can be used
> to debug and tune the performance of AMD P-state driver.
>
> Use the time difference between amd_pstate_update to calculate CPU
> frequency. There could be sleep in arch_freq_get_on_cpu, so do not
> use it here.
>
> Signed-off-by: Jinzhou Su <Jinzhou.Su@....com>
> Signed-off-by: Huang Rui <ray.huang@....com>
I'm not sure what the second sign-off is for.
If this is a maintainer's sign-off, it should be added by the
maintainer himself and you should not add it when submitting the
patch.
> ---
> drivers/cpufreq/amd-pstate-trace.h | 22 ++++++++++-
> drivers/cpufreq/amd-pstate.c | 59 +++++++++++++++++++++++++++++-
> 2 files changed, 78 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/cpufreq/amd-pstate-trace.h b/drivers/cpufreq/amd-pstate-trace.h
> index 647505957d4f..35f38ae67fb1 100644
> --- a/drivers/cpufreq/amd-pstate-trace.h
> +++ b/drivers/cpufreq/amd-pstate-trace.h
> @@ -27,6 +27,10 @@ TRACE_EVENT(amd_pstate_perf,
> TP_PROTO(unsigned long min_perf,
> unsigned long target_perf,
> unsigned long capacity,
> + u64 freq,
> + u64 mperf,
> + u64 aperf,
> + u64 tsc,
> unsigned int cpu_id,
> bool changed,
> bool fast_switch
> @@ -35,6 +39,10 @@ TRACE_EVENT(amd_pstate_perf,
> TP_ARGS(min_perf,
> target_perf,
> capacity,
> + freq,
> + mperf,
> + aperf,
> + tsc,
> cpu_id,
> changed,
> fast_switch
> @@ -44,6 +52,10 @@ TRACE_EVENT(amd_pstate_perf,
> __field(unsigned long, min_perf)
> __field(unsigned long, target_perf)
> __field(unsigned long, capacity)
> + __field(unsigned long long, freq)
> + __field(unsigned long long, mperf)
> + __field(unsigned long long, aperf)
> + __field(unsigned long long, tsc)
> __field(unsigned int, cpu_id)
> __field(bool, changed)
> __field(bool, fast_switch)
> @@ -53,15 +65,23 @@ TRACE_EVENT(amd_pstate_perf,
> __entry->min_perf = min_perf;
> __entry->target_perf = target_perf;
> __entry->capacity = capacity;
> + __entry->freq = freq;
> + __entry->mperf = mperf;
> + __entry->aperf = aperf;
> + __entry->tsc = tsc;
> __entry->cpu_id = cpu_id;
> __entry->changed = changed;
> __entry->fast_switch = fast_switch;
> ),
>
> - TP_printk("amd_min_perf=%lu amd_des_perf=%lu amd_max_perf=%lu cpu_id=%u changed=%s fast_switch=%s",
> + TP_printk("amd_min_perf=%lu amd_des_perf=%lu amd_max_perf=%lu freq=%llu mperf=%llu aperf=%llu tsc=%llu cpu_id=%u changed=%s fast_switch=%s",
> (unsigned long)__entry->min_perf,
> (unsigned long)__entry->target_perf,
> (unsigned long)__entry->capacity,
> + (unsigned long long)__entry->freq,
> + (unsigned long long)__entry->mperf,
> + (unsigned long long)__entry->aperf,
> + (unsigned long long)__entry->tsc,
> (unsigned int)__entry->cpu_id,
> (__entry->changed) ? "true" : "false",
> (__entry->fast_switch) ? "true" : "false"
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index 9ce75ed11f8e..7be38bc6a673 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -65,6 +65,18 @@ MODULE_PARM_DESC(shared_mem,
>
> static struct cpufreq_driver amd_pstate_driver;
>
> +/**
> + * struct amd_aperf_mperf
> + * @aperf: actual performance frequency clock count
> + * @mperf: maximum performance frequency clock count
> + * @tsc: time stamp counter
> + */
> +struct amd_aperf_mperf {
> + u64 aperf;
> + u64 mperf;
> + u64 tsc;
> +};
> +
> /**
> * struct amd_cpudata - private CPU data for AMD P-State
> * @cpu: CPU number
> @@ -81,6 +93,9 @@ static struct cpufreq_driver amd_pstate_driver;
> * @min_freq: the frequency that mapped to lowest_perf
> * @nominal_freq: the frequency that mapped to nominal_perf
> * @lowest_nonlinear_freq: the frequency that mapped to lowest_nonlinear_perf
> + * @cur: Difference of Aperf/Mperf/tsc count between last and current sample
> + * @prev: Last Aperf/Mperf/tsc count value read from register
> + * @freq: current cpu frequency value
> * @boost_supported: check whether the Processor or SBIOS supports boost mode
> *
> * The amd_cpudata is key private data for each CPU thread in AMD P-State, and
> @@ -102,6 +117,10 @@ struct amd_cpudata {
> u32 nominal_freq;
> u32 lowest_nonlinear_freq;
>
> + struct amd_aperf_mperf cur;
> + struct amd_aperf_mperf prev;
> +
> + u64 freq;
> bool boost_supported;
> };
>
> @@ -211,6 +230,39 @@ static inline void amd_pstate_update_perf(struct amd_cpudata *cpudata,
> max_perf, fast_switch);
> }
>
> +static inline bool amd_pstate_sample(struct amd_cpudata *cpudata)
> +{
> + u64 aperf, mperf, tsc;
> + unsigned long flags;
> +
> + local_irq_save(flags);
> + rdmsrl(MSR_IA32_APERF, aperf);
> + rdmsrl(MSR_IA32_MPERF, mperf);
> + tsc = rdtsc();
> +
> + if (cpudata->prev.mperf == mperf || cpudata->prev.tsc == tsc) {
> + local_irq_restore(flags);
> + return false;
> + }
> +
> + local_irq_restore(flags);
> +
> + cpudata->cur.aperf = aperf;
> + cpudata->cur.mperf = mperf;
> + cpudata->cur.tsc = tsc;
> + cpudata->cur.aperf -= cpudata->prev.aperf;
> + cpudata->cur.mperf -= cpudata->prev.mperf;
> + cpudata->cur.tsc -= cpudata->prev.tsc;
> +
> + cpudata->prev.aperf = aperf;
> + cpudata->prev.mperf = mperf;
> + cpudata->prev.tsc = tsc;
> +
> + cpudata->freq = div64_u64((cpudata->cur.aperf * cpu_khz), cpudata->cur.mperf);
> +
> + return true;
> +}
> +
> static void amd_pstate_update(struct amd_cpudata *cpudata, u32 min_perf,
> u32 des_perf, u32 max_perf, bool fast_switch)
> {
> @@ -226,8 +278,11 @@ static void amd_pstate_update(struct amd_cpudata *cpudata, u32 min_perf,
> value &= ~AMD_CPPC_MAX_PERF(~0L);
> value |= AMD_CPPC_MAX_PERF(max_perf);
>
> - trace_amd_pstate_perf(min_perf, des_perf, max_perf,
> - cpudata->cpu, (value != prev), fast_switch);
> + if (trace_amd_pstate_perf_enabled() && amd_pstate_sample(cpudata)) {
> + trace_amd_pstate_perf(min_perf, des_perf, max_perf, cpudata->freq,
> + cpudata->cur.mperf, cpudata->cur.aperf, cpudata->cur.tsc,
> + cpudata->cpu, (value != prev), fast_switch);
> + }
>
> if (value == prev)
> return;
> --
> 2.27.0
>
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