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authorKonstantin Khlebnikov <khlebnikov@yandex-team.ru>2020-04-29 19:23:41 +0300
committerArnaldo Carvalho de Melo <acme@redhat.com>2020-05-05 22:35:29 +0300
commitbb629484d924118e3b1d8652177040115adcba01 (patch)
tree63c5b651859bbc6ad189d029efa52f020a65ed20 /tools/perf/util/smt.c
parent846de4371fdfddfa49481e3d04884539870dc127 (diff)
downloadlinux-bb629484d924118e3b1d8652177040115adcba01.tar.xz
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>
Diffstat (limited to 'tools/perf/util/smt.c')
-rw-r--r--tools/perf/util/smt.c4
1 files changed, 4 insertions, 0 deletions
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;