linux-kernel - Re: [PATCH v3] perf/x86/rapl: Fix the energy-pkg event for AMD CPUs

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Message-ID: <b34e30bc-a003-4529-bcfe-8189ca7ddc5b@amd.com>
Date: Thu, 5 Sep 2024 17:49:44 +0530
From: Dhananjay Ugwekar <Dhananjay.Ugwekar@....com>
To: peterz@...radead.org, mingo@...hat.com, acme@...nel.org,
 namhyung@...nel.org, mark.rutland@....com,
 alexander.shishkin@...ux.intel.com, jolsa@...nel.org, irogers@...gle.com,
 adrian.hunter@...el.com, kan.liang@...ux.intel.com, tglx@...utronix.de,
 bp@...en8.de, dave.hansen@...ux.intel.com, x86@...nel.org, hpa@...or.com
Cc: gautham.shenoy@....com, ravi.bangoria@....com,
 linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] perf/x86/rapl: Fix the energy-pkg event for AMD CPUs

On 9/4/2024 3:39 PM, Dhananjay Ugwekar wrote:
> After commit ("x86/cpu/topology: Add support for the AMD 0x80000026 leaf"),
> on AMD processors that support extended CPUID leaf 0x80000026, the
> topology_die_cpumask() and topology_logical_die_id() macros, no longer
> return the package cpumask and package id, instead they return the CCD
> (Core Complex Die) mask and id respectively. This leads to the energy-pkg
> event scope to be modified to CCD instead of package.
> 
> So, change the PMU scope for AMD and Hygon back to package.
> 
> On a 12 CCD 1 Package AMD Zen4 Genoa machine:
> 
> Before:
> $ cat /sys/devices/power/cpumask
> 0,8,16,24,32,40,48,56,64,72,80,88.
> 
> The expected cpumask here is supposed to be just "0", as it is a package
> scope event, only one CPU will be collecting the event for all the CPUs in
> the package.
> 
> After:
> $ cat /sys/devices/power/cpumask
> 0
> 
> Signed-off-by: Dhananjay Ugwekar <Dhananjay.Ugwekar@....com>
> ---
> v2 Link: https://lore.kernel.org/all/20240730044917.4680-2-Dhananjay.Ugwekar@amd.com/
> 
> Changes from v2:
> * Rebase on top of kan.liang's PMU scope patchset [1]
> * Set pmu.scope variable to package for AMD/Hygon CPUs
> 
> tip/master + PMU scope patchset [1] to be taken as base for testing this patch. 
> 
> [1]: https://lore.kernel.org/all/20240802151643.1691631-1-kan.liang@linux.intel.com/
> ---
>  arch/x86/events/rapl.c | 33 +++++++++++++++++++++++++++++++--
>  1 file changed, 31 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/events/rapl.c b/arch/x86/events/rapl.c
> index b70ad880c5bc..0c57dd5aa767 100644
> --- a/arch/x86/events/rapl.c
> +++ b/arch/x86/events/rapl.c
> @@ -139,9 +139,32 @@ static unsigned int rapl_cntr_mask;
>  static u64 rapl_timer_ms;
>  static struct perf_msr *rapl_msrs;
>  
> +/*
> + * RAPL Package energy counter scope:
> + * 1. AMD/HYGON platforms have a per-PKG package energy counter
> + * 2. For Intel platforms
> + *	2.1. CLX-AP is multi-die and its RAPL MSRs are die-scope
> + *	2.2. Other Intel platforms are single die systems so the scope can be
> + *	     considered as either pkg-scope or die-scope, and we are considering
> + *	     them as die-scope.
> + */
> +#define rapl_pmu_is_pkg_scope()				\
> +	(boot_cpu_data.x86_vendor == X86_VENDOR_AMD ||	\
> +	 boot_cpu_data.x86_vendor == X86_VENDOR_HYGON)
> +
> +/*
> + * Helper function to get the correct topology id according to the
> + * RAPL PMU scope.
> + */
> +static inline unsigned int get_rapl_pmu_idx(int cpu)
> +{
> +	return rapl_pmu_is_pkg_scope() ? topology_logical_package_id(cpu) :
> +					 topology_logical_die_id(cpu);
> +}
> +
>  static inline struct rapl_pmu *cpu_to_rapl_pmu(unsigned int cpu)
>  {
> -	unsigned int rapl_pmu_idx = topology_logical_die_id(cpu);
> +	unsigned int rapl_pmu_idx = get_rapl_pmu_idx(cpu);
>  
>  	/*
>  	 * The unsigned check also catches the '-1' return value for non
> @@ -617,7 +640,7 @@ static void __init init_rapl_pmu(void)
>  		pmu->timer_interval = ms_to_ktime(rapl_timer_ms);
>  		rapl_hrtimer_init(pmu);
>  
> -		rapl_pmus->pmus[topology_logical_die_id(cpu)] = pmu;
> +		rapl_pmus->pmus[get_rapl_pmu_idx(cpu)] = pmu;
>  	}
>  
>  	cpus_read_unlock();
> @@ -646,6 +669,12 @@ static int __init init_rapl_pmus(void)
>  	rapl_pmus->pmu.module		= THIS_MODULE;
>  	rapl_pmus->pmu.scope		= PERF_PMU_SCOPE_DIE;
>  	rapl_pmus->pmu.capabilities	= PERF_PMU_CAP_NO_EXCLUDE;
> +
> +	if (rapl_pmu_is_pkg_scope()) {
> +		rapl_pmus->nr_rapl_pmu	= topology_max_packages();

Just noticed, better to update nr_rapl_pmu before we allocate the memory for rapl_pmus at
"rapl_pmus = kzalloc(struct_size(rapl_pmus, rapl_pmu, nr_rapl_pmu), GFP_KERNEL);", so that
we dont waste memory, will fix this and post new version.

Thanks,
Dhananjay

> +		rapl_pmus->pmu.scope	= PERF_PMU_SCOPE_PKG;
> +	}
> +
>  	return 0;
>  }
>