linux-kernel - Re: [PATCH v2 2/3] perf mem amd: Fix perf_pmus__num_mem

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Date:   Wed, 14 Jun 2023 23:02:12 -0700
From:   Ian Rogers <irogers@...gle.com>
To:     Ravi Bangoria <ravi.bangoria@....com>
Cc:     acme@...nel.org, jolsa@...nel.org, namhyung@...nel.org,
        peterz@...radead.org, james.clark@....com, alisaidi@...zon.com,
        leo.yan@...aro.org, adrian.hunter@...el.com,
        kan.liang@...ux.intel.com, mark.rutland@....com,
        maddy@...ux.ibm.com, tmricht@...ux.ibm.com,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org,
        sandipan.das@....com, ananth.narayan@....com,
        santosh.shukla@....com
Subject: Re: [PATCH v2 2/3] perf mem amd: Fix perf_pmus__num_mem_pmus()

On Wed, Jun 14, 2023 at 10:18 PM Ravi Bangoria <ravi.bangoria@....com> wrote:
>
> perf mem/c2c on AMD internally uses IBS OP PMU, not the core PMU. Also,
> AMD platforms does not have heterogeneous PMUs.
>
> Signed-off-by: Ravi Bangoria <ravi.bangoria@....com>
> ---
>  tools/perf/arch/x86/util/pmu.c | 12 ++++++++++++
>  tools/perf/util/pmus.c         |  2 +-
>  2 files changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/tools/perf/arch/x86/util/pmu.c b/tools/perf/arch/x86/util/pmu.c
> index 3c0de3370d7e..f3534a791e79 100644
> --- a/tools/perf/arch/x86/util/pmu.c
> +++ b/tools/perf/arch/x86/util/pmu.c
> @@ -14,6 +14,8 @@
>  #include "../../../util/intel-bts.h"
>  #include "../../../util/pmu.h"
>  #include "../../../util/fncache.h"
> +#include "../../../util/pmus.h"
> +#include "env.h"
>
>  struct pmu_alias {
>         char *name;
> @@ -168,3 +170,13 @@ char *pmu_find_alias_name(const char *name)
>
>         return __pmu_find_alias_name(name);
>  }
> +
> +int perf_pmus__num_mem_pmus(void)
> +{
> +       /* AMD uses IBS OP pmu for perf mem/c2c */

nit: could we just add:
AMD uses IBS OP pmu and not a core PMU for perf mem/c2c

Thanks,
Ian

> +       if (x86__is_amd_cpu())
> +               return 1;
> +
> +       /* Intel uses core pmus for perf mem/c2c */
> +       return perf_pmus__num_core_pmus();
> +}
> diff --git a/tools/perf/util/pmus.c b/tools/perf/util/pmus.c
> index 8c50ab8894b7..a2032c1b7644 100644
> --- a/tools/perf/util/pmus.c
> +++ b/tools/perf/util/pmus.c
> @@ -242,7 +242,7 @@ const struct perf_pmu *perf_pmus__pmu_for_pmu_filter(const char *str)
>         return NULL;
>  }
>
> -int perf_pmus__num_mem_pmus(void)
> +int __weak perf_pmus__num_mem_pmus(void)
>  {
>         /* All core PMUs are for mem events. */
>         return perf_pmus__num_core_pmus();
> --
> 2.40.1
>