| From | Arnaldo Carvalho de Melo <> | Subject | [PATCH 38/91] perf tools: Simplify checking if SMT is active. | Date | Wed, 6 May 2020 12:21:41 -0300 |
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From: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
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> --- tools/perf/util/smt.c | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/tools/perf/util/smt.c b/tools/perf/util/smt.c index 8481842e9edb..20bacd5972ad 100644 --- a/tools/perf/util/smt.c +++ b/tools/perf/util/smt.c @@ -15,6 +15,9 @@ int smt_on(void) if (cached) return cached_result; + if (sysfs__read_int("devices/system/cpu/smt/active", &cached_result) > 0) + goto done; + ncpu = sysconf(_SC_NPROCESSORS_CONF); for (cpu = 0; cpu < ncpu; cpu++) { unsigned long long siblings; @@ -42,6 +45,7 @@ int smt_on(void) } if (!cached) { cached_result = 0; +done: cached = true; } return cached_result; -- 2.21.1
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