linux-kernel - Re: [PATCH v1] perf vendor power9 nest metrics: Correct unit from MB to MiB

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Message-ID: <CAP-5=fV1bobHM5bT8xU7sxZAFt03XNaXwTQVGj3hm9RyKsH3fw@mail.gmail.com>
Date: Wed, 12 Nov 2025 11:31:22 -0800
From: Ian Rogers <irogers@...gle.com>
To: Athira Rajeev <atrajeev@...ux.vnet.ibm.com>, Kajol Jain <kjain@...ux.ibm.com>, 
	Madhavan Srinivasan <maddy@...ux.ibm.com>
Cc: linux-perf-users@...r.kernel.org, Jiri Olsa <jolsa@...nel.org>, 
	linux-kernel@...r.kernel.org, Adrian Hunter <adrian.hunter@...el.com>, 
	Arnaldo Carvalho de Melo <acme@...nel.org>, Ian Rogers <irogers@...gle.com>, 
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Peter Zijlstra <peterz@...radead.org>, 
	Namhyung Kim <namhyung@...nel.org>, Ingo Molnar <mingo@...hat.com>
Subject: Re: [PATCH v1] perf vendor power9 nest metrics: Correct unit from MB
 to MiB

On Fri, Oct 31, 2025 at 9:26 AM Ian Rogers <irogers@...gle.com> wrote:
>
> 6.1e-5 is very close to 1/16384, where 16384 is 2^14, i.e. a power of
> 2. When units are in powers of 2 the IEC unit is MiB (mebibytes)
> rather than MB (megabytes) where the values are powers of 10. This
> patch corrects the unit for uniformity and because such units may be
> pattern matched against.
>
> Signed-off-by: Ian Rogers <irogers@...gle.com>

Ping.

Thanks,
Ian

> ---
>  .../perf/pmu-events/arch/powerpc/power9/nest_metrics.json | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/tools/perf/pmu-events/arch/powerpc/power9/nest_metrics.json b/tools/perf/pmu-events/arch/powerpc/power9/nest_metrics.json
> index 7a5d1bf543f8..8d028a7c2777 100644
> --- a/tools/perf/pmu-events/arch/powerpc/power9/nest_metrics.json
> +++ b/tools/perf/pmu-events/arch/powerpc/power9/nest_metrics.json
> @@ -29,25 +29,25 @@
>         "MetricExpr" : "nest_mcs01_imc@...MCS01_128B_RD_DISP_PORT01@ + nest_mcs01_imc@...MCS01_128B_RD_DISP_PORT23@",
>         "MetricName" : "mcs01-read",
>         "MetricGroup" : "memory-bandwidth",
> -       "ScaleUnit": "6.1e-5MB"
> +       "ScaleUnit": "6.1e-5MiB"
>      },
>      {
>         "MetricExpr" : "nest_mcs23_imc@...MCS23_128B_RD_DISP_PORT01@ + nest_mcs23_imc@...MCS23_128B_RD_DISP_PORT23@",
>         "MetricName" : "mcs23-read",
>         "MetricGroup" : "memory-bandwidth",
> -       "ScaleUnit": "6.1e-5MB"
> +       "ScaleUnit": "6.1e-5MiB"
>      },
>      {
>         "MetricExpr" : "nest_mcs01_imc@...MCS01_128B_WR_DISP_PORT01@ + nest_mcs01_imc@...MCS01_128B_WR_DISP_PORT23@",
>         "MetricName" : "mcs01-write",
>         "MetricGroup" : "memory-bandwidth",
> -       "ScaleUnit": "6.1e-5MB"
> +       "ScaleUnit": "6.1e-5MiB"
>      },
>      {
>         "MetricExpr" : "nest_mcs23_imc@...MCS23_128B_WR_DISP_PORT01@ + nest_mcs23_imc@...MCS23_128B_WR_DISP_PORT23@",
>         "MetricName" : "mcs23-write",
>         "MetricGroup" : "memory-bandwidth",
> -       "ScaleUnit": "6.1e-5MB"
> +       "ScaleUnit": "6.1e-5MiB"
>      },
>      {
>         "MetricExpr" : "nest_powerbus0_imc@...PB_CYC@",
> --
> 2.51.1.930.gacf6e81ea2-goog
>