Commit bb629484 authored Apr 29, 2020 by Konstantin Khlebnikov Committed by Arnaldo Carvalho de Melo May 05, 2020

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>

parent 846de437

tools/perf/util/smt.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -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;

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