linux-kernel - Re: [PATCH v1 1/2] perf arm-spe: Support multiple Arm SPE PMUs

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Date: Thu, 27 Jun 2024 15:37:55 -0700
From: Namhyung Kim <namhyung@...nel.org>
To: Leo Yan <leo.yan@....com>
Cc: Ian Rogers <irogers@...gle.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	James Clark <james.clark@....com>,
	Suzuki K Poulose <suzuki.poulose@....com>,
	Mike Leach <mike.leach@...aro.org>,
	John Garry <john.g.garry@...cle.com>, Will Deacon <will@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>, Mark Rutland <mark.rutland@....com>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Adrian Hunter <adrian.hunter@...el.com>,
	"Liang, Kan" <kan.liang@...ux.intel.com>,
	Kajol Jain <kjain@...ux.ibm.com>, coresight@...ts.linaro.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 1/2] perf arm-spe: Support multiple Arm SPE PMUs

Hello Leo,

On Tue, Jun 25, 2024 at 05:49:16PM +0100, Leo Yan wrote:
> Hi Ian,
> 
> On 6/24/24 17:16, Ian Rogers wrote:
> > On Sun, Jun 23, 2024 at 6:34 AM Leo Yan <leo.yan@....com> wrote:
> > > 
> > > A platform can have more than one Arm SPE PMU. For example, a system
> > > with multiple clusters may have each cluster enabled with its own Arm
> > > SPE instance. In such case, the PMU devices will be named 'arm_spe_0',
> > > 'arm_spe_1', and so on.
> > > 
> > > Currently, the tool only supports 'arm_spe_0'. This commit extends
> > > support to multiple Arm SPE PMUs by detecting the substring 'arm_spe'.
> > > 
> > > Signed-off-by: Leo Yan <leo.yan@....com>
> > > ---
> > >   tools/perf/arch/arm/util/pmu.c | 2 +-
> > >   1 file changed, 1 insertion(+), 1 deletion(-)
> > > 
> > > diff --git a/tools/perf/arch/arm/util/pmu.c b/tools/perf/arch/arm/util/pmu.c
> > > index 8b7cb68ba1a8..29cfa1e427ed 100644
> > > --- a/tools/perf/arch/arm/util/pmu.c
> > > +++ b/tools/perf/arch/arm/util/pmu.c
> > > @@ -27,7 +27,7 @@ void perf_pmu__arch_init(struct perf_pmu *pmu __maybe_unused)
> > >                  pmu->selectable = true;
> > >                  pmu->is_uncore = false;
> > >                  pmu->perf_event_attr_init_default = arm_spe_pmu_default_config;
> > > -               if (!strcmp(pmu->name, "arm_spe_0"))
> > > +               if (strstr(pmu->name, "arm_spe"))
> > 
> > Why not use strstarts?
> 
> Indeed, strstarts() is better, will spin for this.
> 
> Thank for suggestion.

Probably we need to check the last underscore too to prevent potential
name clashes..

Thanks,
Namhyung