The following commit has been merged into the perf/core branch of tip:
Commit-ID: bb629484d924118e3b1d8652177040115adcba01
Gitweb: https://git.kernel.org/tip/bb629484d924118e3b1d8652177040115adcba01
Author: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxxxxxx>
AuthorDate: Wed, 29 Apr 2020 19:23:41 +03:00
Committer: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitterDate: Tue, 05 May 2020 16:35:29 -03:00
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@xxxxxxxxxxxxxx>
Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Cc: Dmitry Monakhov <dmtrmonakhov@xxxxxxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Link: http://lore.kernel.org/lkml/158817741394.748034.9273604089138009552.stgit@buzz
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
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 8481842..20bacd5 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;
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