Messages in this thread | | | Subject | Re: [RFCv2 4/4] perf: util: support sysfs supported_cpumask file | From | Suzuki K Poulose <> | Date | Mon, 18 Jul 2016 17:38:16 +0100 |
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On 15/07/16 11:08, Mark Rutland wrote: > For system PMUs, the perf tools have long expected a cpumask file under > sysfs, describing the single CPU which they support events being > opened/handled on. Prior patches in this series have reworked this > support to support multiple CPUs in a mask, as is required to handle > heterogeneous CPU PMUs. > > Unfortunately, adding a cpumask file to CPU PMUs would break existing > userspace. Prior to this series, perf record will refuse to open events, > and perf stat may unexpectedly block at exit time. In the absence of a > cpumask, perf stat is functional. > > To address this, this patch adds support for a new file, > supported_cpumask, which can be used to describe heterogeneous CPUs, > without the risk of breaking existing userspace binaries. > > Signed-off-by: Mark Rutland <mark.rutland@arm.com> > --- > tools/perf/util/pmu.c | 15 ++++++++++++--- > 1 file changed, 12 insertions(+), 3 deletions(-) > > diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c > index ddb0261..06c985c 100644 > --- a/tools/perf/util/pmu.c > +++ b/tools/perf/util/pmu.c > @@ -445,14 +445,23 @@ static struct cpu_map *pmu_cpumask(const char *name) > FILE *file; > struct cpu_map *cpus; > const char *sysfs = sysfs__mountpoint(); > + const char *path_template[] = { > + "%s/bus/event_source/devices/%s/cpumask", > + "%s/bus/event_source/devices/%s/supported_cpumask", > + NULL > + }; > + unsigned int i; > > if (!sysfs) > return NULL; > > - snprintf(path, PATH_MAX, > - "%s/bus/event_source/devices/%s/cpumask", sysfs, name); > + for (i = 0; i < ARRAY_SIZE(path_template); i++) {
The check could be "path_template[i]" to avoid an iteration with NULL template.
> + snprintf(path, PATH_MAX, *path_template, sysfs, name);
Btw, did you mean to use path_template[i] here instead of *path_template ?
> + if (stat(path, &st) == 0) > + break; > + } > > - if (stat(path, &st) < 0) > + if (!*path_template)
Same here ?
> return NULL;
Suzuki
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