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Message-ID: <20200422114122.GG962614@krava>
Date: Wed, 22 Apr 2020 13:41:22 +0200
From: Jiri Olsa <jolsa@...hat.com>
To: John Garry <john.garry@...wei.com>
Cc: peterz@...radead.org, mingo@...hat.com, acme@...nel.org,
mark.rutland@....com, alexander.shishkin@...ux.intel.com,
namhyung@...nel.org, will@...nel.org, ak@...ux.intel.com,
linuxarm@...wei.com, linux-kernel@...r.kernel.org,
qiangqing.zhang@....com, irogers@...gle.com, robin.murphy@....com,
zhangshaokun@...ilicon.com, linux-arm-kernel@...ts.infradead.org
Subject: Re: [RFC PATCH v2 07/13] perf pmu: Add pmu_id()
On Fri, Apr 17, 2020 at 06:41:18PM +0800, John Garry wrote:
> Add a function to read the PMU id sysfs entry. We only do it for uncore
> PMUs where this would be relevant.
>
> Signed-off-by: John Garry <john.garry@...wei.com>
> ---
> tools/perf/util/pmu.c | 36 ++++++++++++++++++++++++++++++++++++
> tools/perf/util/pmu.h | 1 +
> 2 files changed, 37 insertions(+)
>
> diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
> index ef6a63f3d386..6a67c6a28d08 100644
> --- a/tools/perf/util/pmu.c
> +++ b/tools/perf/util/pmu.c
> @@ -594,6 +594,7 @@ static struct perf_cpu_map *__pmu_cpumask(const char *path)
> * Uncore PMUs have a "cpumask" file under sysfs. CPU PMUs (e.g. on arm/arm64)
> * may have a "cpus" file.
> */
> +#define CPUS_TEMPLATE_ID "%s/bus/event_source/devices/%s/identifier"
> #define CPUS_TEMPLATE_UNCORE "%s/bus/event_source/devices/%s/cpumask"
> #define CPUS_TEMPLATE_CPU "%s/bus/event_source/devices/%s/cpus"
>
> @@ -632,6 +633,39 @@ static bool pmu_is_uncore(const char *name)
> return file_available(path);
> }
>
> +static char *pmu_id(const char *name)
> +{
> + char path[PATH_MAX], *id;
> + const char *sysfs;
> + FILE *file;
> + int n;
> +
> + sysfs = sysfs__mountpoint();
> + snprintf(path, PATH_MAX, CPUS_TEMPLATE_ID, sysfs, name);
> +
> + id = malloc(PATH_MAX);
> + if (!id)
> + return NULL;
> +
> + file = fopen(path, "r");
> + if (!file) {
> + free(id);
> + return NULL;
> + }
> +
> + n = fscanf(file, "%s", id);
> +
> + fclose(file);
> +
> + if (!n) {
> + free(id);
> + return NULL;
> + }
> +
> + return id;
> +}
I still need to go through this patchset in more detail,
but just quick note, that we have sysfs__read_str that you
could use in here
jirka
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