Re: [PATCH v1 14/14] libperf cpumap: Document perf_cpu_map__nr's behavior

From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: James Clark <james.clark@arm.com>
Cc: "Ian Rogers" <irogers@google.com>,
	"Peter Zijlstra" <peterz@infradead.org>,
	"Ingo Molnar" <mingo@redhat.com>,
	"Mark Rutland" <mark.rutland@arm.com>,
	"Alexander Shishkin" <alexander.shishkin@linux.intel.com>,
	"Jiri Olsa" <jolsa@kernel.org>,
	"Namhyung Kim" <namhyung@kernel.org>,
	"Adrian Hunter" <adrian.hunter@intel.com>,
	"Suzuki K Poulose" <suzuki.poulose@arm.com>,
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	"Leo Yan" <leo.yan@linaro.org>,
	"John Garry" <john.g.garry@oracle.com>,
	"Will Deacon" <will@kernel.org>,
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	"Huacai Chen" <chenhuacai@kernel.org>,
	"Yanteng Si" <siyanteng@loongson.cn>,
	linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org,
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Subject: Re: [PATCH v1 14/14] libperf cpumap: Document perf_cpu_map__nr's behavior
Date: Mon, 18 Dec 2023 17:36:39 -0300	[thread overview]
Message-ID: <ZYCtV6YcDLpgau75@kernel.org> (raw)
In-Reply-To: <0e1ca950-b5a4-1e08-8696-4e3e12e21b19@arm.com>

Em Tue, Dec 12, 2023 at 03:20:47PM +0000, James Clark escreveu:
> On 29/11/2023 06:02, Ian Rogers wrote:
> >  LIBPERF_API void perf_cpu_map__put(struct perf_cpu_map *map);
> > +/**
> > + * perf_cpu_map__cpu - get the CPU value at the given index. Returns -1 if index
> > + *                     is invalid.
> > + */
> >  LIBPERF_API struct perf_cpu perf_cpu_map__cpu(const struct perf_cpu_map *cpus, int idx);
> > +/**
> > + * perf_cpu_map__nr - for an empty map returns 1, as perf_cpu_map__cpu returns a
> > + *                    cpu of -1 for an invalid index, this makes an empty map
> > + *                    look like it contains the "any CPU"/dummy value. Otherwise
> > + *                    the result is the number CPUs in the map plus one if the
> > + *                    "any CPU"/dummy value is present.
> 
> Hmmm... I'm not sure whether to laugh or cry at that API.
> 
> Reviewed-by: James Clark <james.clark@arm.com>

Thanks, applied to perf-tools-next.

- Arnaldo