linux-kernel - Re: [PATCH 3/3] perf/x86/rapl: add AMD Fam17h RAPL support

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Date:   Mon, 18 May 2020 13:16:41 -0700
From:   Stephane Eranian <eranian@...gle.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     LKML <linux-kernel@...r.kernel.org>, mingo@...e.hu,
        Ian Rogers <irogers@...gle.com>,
        "Phillips, Kim" <kim.phillips@....com>,
        Jiri Olsa <jolsa@...hat.com>
Subject: Re: [PATCH 3/3] perf/x86/rapl: add AMD Fam17h RAPL support

On Mon, May 18, 2020 at 2:34 AM Peter Zijlstra <peterz@...radead.org> wrote:
>
> On Fri, May 15, 2020 at 02:57:33PM -0700, Stephane Eranian wrote:
>
> > +static struct perf_msr amd_rapl_msrs[] = {
> > +     [PERF_RAPL_PP0]  = { 0, &rapl_events_cores_group, NULL},
> > +     [PERF_RAPL_PKG]  = { MSR_AMD_PKG_ENERGY_STATUS,  &rapl_events_pkg_group,   test_msr },
> > +     [PERF_RAPL_RAM]  = { 0, &rapl_events_ram_group,   NULL},
> > +     [PERF_RAPL_PP1]  = { 0, &rapl_events_gpu_group,   NULL},
> > +     [PERF_RAPL_PSYS] = { 0, &rapl_events_psys_group,  NULL},
> > +};
>
> Why have those !PKG things initialized? Wouldn't they default to 0
> anyway? If not, surely { 0, } is sufficient.

Yes, but that assumes that perf_msr_probe() is fixed to not expect a grp.
I think it is best to fix perf_msr_probe(). I already fixed one
problem, I'll fix this one as well.