linux-kernel - Re: [PATCH 01/15] cpufreq/amd-pstate: Add trace event for EPP perf updates

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Message-ID: <Z1KPLzoKy8s35Zf7@BLRRASHENOY1.amd.com>
Date: Fri, 6 Dec 2024 11:14:15 +0530
From: "Gautham R. Shenoy" <gautham.shenoy@....com>
To: Mario Limonciello <mario.limonciello@....com>
Cc: Perry Yuan <perry.yuan@....com>, linux-kernel@...r.kernel.org,
	linux-pm@...r.kernel.org,
	Dhananjay Ugwekar <Dhananjay.Ugwekar@....com>
Subject: Re: [PATCH 01/15] cpufreq/amd-pstate: Add trace event for EPP perf
 updates

On Thu, Dec 05, 2024 at 04:28:33PM -0600, Mario Limonciello wrote:
> In "active" mode the most important thing for debugging whether
> an issue is hardware or software based is to look at what was the
> last thing written to the CPPC request MSR or shared memory region.
> 
> The 'amd_pstate_epp_perf' trace event shows the values being written
> for all CPUs.
> 
> Signed-off-by: Mario Limonciello <mario.limonciello@....com>

Thank you Mario for adding this. This is useful for correlating the
frequencies requested by the userspace with the min_per/max_perf/epp
values chosen by the hardware.

The patch looks good to me.

Reviewed-by: Gautham R. Shenoy <gautham.shenoy@....com>

--
Thanks and Regards
gautham.

> ---
>  drivers/cpufreq/amd-pstate-trace.h | 45 ++++++++++++++++++++++++++++++
>  drivers/cpufreq/amd-pstate.c       | 28 +++++++++++++++++++
>  2 files changed, 73 insertions(+)
> 
> diff --git a/drivers/cpufreq/amd-pstate-trace.h b/drivers/cpufreq/amd-pstate-trace.h
> index 35f38ae67fb13..e2221a4b6901c 100644
> --- a/drivers/cpufreq/amd-pstate-trace.h
> +++ b/drivers/cpufreq/amd-pstate-trace.h
> @@ -88,6 +88,51 @@ TRACE_EVENT(amd_pstate_perf,
>  		 )
>  );
>  
> +TRACE_EVENT(amd_pstate_epp_perf,
> +
> +	TP_PROTO(unsigned int cpu_id,
> +		 unsigned int highest_perf,
> +		 unsigned int epp,
> +		 unsigned int min_perf,
> +		 unsigned int max_perf,
> +		 bool boost
> +		 ),
> +
> +	TP_ARGS(cpu_id,
> +		highest_perf,
> +		epp,
> +		min_perf,
> +		max_perf,
> +		boost),
> +
> +	TP_STRUCT__entry(
> +		__field(unsigned int, cpu_id)
> +		__field(unsigned int, highest_perf)
> +		__field(unsigned int, epp)
> +		__field(unsigned int, min_perf)
> +		__field(unsigned int, max_perf)
> +		__field(bool, boost)
> +		),
> +
> +	TP_fast_assign(
> +		__entry->cpu_id = cpu_id;
> +		__entry->highest_perf = highest_perf;
> +		__entry->epp = epp;
> +		__entry->min_perf = min_perf;
> +		__entry->max_perf = max_perf;
> +		__entry->boost = boost;
> +		),
> +
> +	TP_printk("cpu%u: [%u<->%u]/%u, epp=%u, boost=%u",
> +		  (unsigned int)__entry->cpu_id,
> +		  (unsigned int)__entry->min_perf,
> +		  (unsigned int)__entry->max_perf,
> +		  (unsigned int)__entry->highest_perf,
> +		  (unsigned int)__entry->epp,
> +		  (bool)__entry->boost
> +		 )
> +);
> +
>  #endif /* _AMD_PSTATE_TRACE_H */
>  
>  /* This part must be outside protection */
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index 66fb7aee95d24..4d1da49d345ec 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -324,6 +324,14 @@ static int amd_pstate_set_energy_pref_index(struct amd_cpudata *cpudata,
>  		return -EBUSY;
>  	}
>  
> +	if (trace_amd_pstate_epp_perf_enabled()) {
> +		trace_amd_pstate_epp_perf(cpudata->cpu, cpudata->highest_perf,
> +					  epp,
> +					  AMD_CPPC_MIN_PERF(cpudata->cppc_req_cached),
> +					  AMD_CPPC_MAX_PERF(cpudata->cppc_req_cached),
> +					  cpudata->boost_state);
> +	}
> +
>  	ret = amd_pstate_set_epp(cpudata, epp);
>  
>  	return ret;
> @@ -1596,6 +1604,13 @@ static int amd_pstate_epp_update_limit(struct cpufreq_policy *policy)
>  
>  	WRITE_ONCE(cpudata->cppc_req_cached, value);
>  
> +	if (trace_amd_pstate_epp_perf_enabled()) {
> +		trace_amd_pstate_epp_perf(cpudata->cpu, cpudata->highest_perf, epp,
> +					  cpudata->min_limit_perf,
> +					  cpudata->max_limit_perf,
> +					  cpudata->boost_state);
> +	}
> +
>  	amd_pstate_update_perf(cpudata, cpudata->min_limit_perf, 0U,
>  			       cpudata->max_limit_perf, false);
>  
> @@ -1639,6 +1654,13 @@ static void amd_pstate_epp_reenable(struct amd_cpudata *cpudata)
>  
>  	max_perf = READ_ONCE(cpudata->highest_perf);
>  
> +	if (trace_amd_pstate_epp_perf_enabled()) {
> +		trace_amd_pstate_epp_perf(cpudata->cpu, cpudata->highest_perf,
> +					  cpudata->epp_cached,
> +					  AMD_CPPC_MIN_PERF(cpudata->cppc_req_cached),
> +					  max_perf, cpudata->boost_state);
> +	}
> +
>  	amd_pstate_update_perf(cpudata, 0, 0, max_perf, false);
>  	amd_pstate_set_epp(cpudata, cpudata->epp_cached);
>  }
> @@ -1667,6 +1689,12 @@ static int amd_pstate_epp_cpu_offline(struct cpufreq_policy *policy)
>  
>  	mutex_lock(&amd_pstate_limits_lock);
>  
> +	if (trace_amd_pstate_epp_perf_enabled()) {
> +		trace_amd_pstate_epp_perf(cpudata->cpu, cpudata->highest_perf,
> +					  AMD_CPPC_EPP_BALANCE_POWERSAVE,
> +					  min_perf, min_perf, cpudata->boost_state);
> +	}
> +
>  	amd_pstate_update_perf(cpudata, min_perf, 0, min_perf, false);
>  	amd_pstate_set_epp(cpudata, AMD_CPPC_EPP_BALANCE_POWERSAVE);
>  
> -- 
> 2.43.0
>