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perf tools: Simplify checking if SMT is active. 

SMT now could be disabled via "/sys/devices/system/cpu/smt/control".

Status is shown in "/sys/devices/system/cpu/smt/active" simply as "0" / "1".

If this knob isn't here then fallback to checking topology as before.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Dmitry Monakhov <dmtrmonakhov@yandex-team.ru>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/158817741394.748034.9273604089138009552.stgit@buzz
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Konstantin Khlebnikov 2020-04-29 19:23:41 +03:00 committed by Arnaldo Carvalho de Melo
parent 846de4371f
commit bb629484d9
1 changed files with 4 additions and 0 deletions
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4
tools/perf/util/smt.c
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@ -15,6 +15,9 @@ int smt_on(void)
if (cached) if (cached)
return cached_result; return cached_result;
if (sysfs__read_int("devices/system/cpu/smt/active", &cached_result) > 0)
goto done;
ncpu = sysconf(_SC_NPROCESSORS_CONF); ncpu = sysconf(_SC_NPROCESSORS_CONF);
for (cpu = 0; cpu < ncpu; cpu++) { for (cpu = 0; cpu < ncpu; cpu++) {
unsigned long long siblings; unsigned long long siblings;
@ -42,6 +45,7 @@ int smt_on(void)
} }
if (!cached) { if (!cached) {
cached_result = 0; cached_result = 0;
done:
cached = true; cached = true;
} }
return cached_result; return cached_result;