From: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
To: linux-kernel@vger.kernel.org,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>
Cc: Kan Liang <kan.liang@linux.intel.com>,
Jiri Olsa <jolsa@kernel.org>, Andi Kleen <ak@linux.intel.com>,
Dmitry Monakhov <dmtrmonakhov@yandex-team.ru>
Subject: [PATCH v2 3/3] perf tool: simplify checking active smt
Date: Wed, 29 Apr 2020 19:23:41 +0300 [thread overview]
Message-ID: <158817741394.748034.9273604089138009552.stgit@buzz> (raw)
In-Reply-To: <158817718710.747528.11009278875028211991.stgit@buzz>
SMT now could be disabled via "/sys/devices/system/cpu/smt/control".
Status 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>
---
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 dc37b5abd1c3..c398528d1006 100644
--- a/tools/perf/util/smt.c
+++ b/tools/perf/util/smt.c
@@ -19,6 +19,9 @@ int smt_on(void)
if (cached)
return cached_result;
+ if (sysfs__read_int("devices/system/cpu/smt/active", &active) > 0)
+ goto done;
+
ncpu = sysconf(_SC_NPROCESSORS_CONF);
for (cpu = 0; cpu < ncpu; cpu++) {
char fn[256];
@@ -37,6 +40,7 @@ int smt_on(void)
active = str && (strchr(str, ',') != NULL || strchr(str, '-') != NULL);
free(str);
+done:
if (!cached) {
cached_result = active;
cached = true;
next prev parent reply other threads:[~2020-04-29 16:23 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-29 16:19 [PATCH v2 1/3] perf tool: fix reading new topology attribute "core_cpus" Konstantin Khlebnikov
2020-04-29 16:22 ` [PATCH v2 2/3] perf tool: fix detecting smt at machines with more than 32 cpus Konstantin Khlebnikov
2020-04-29 18:13 ` Arnaldo Carvalho de Melo
2020-04-29 18:38 ` Konstantin Khlebnikov
2020-04-30 13:37 ` Arnaldo Carvalho de Melo
2020-04-29 16:23 ` Konstantin Khlebnikov [this message]
2020-04-29 18:16 ` [PATCH v2 3/3] perf tool: simplify checking active smt Arnaldo Carvalho de Melo
2020-05-08 13:05 ` [tip: perf/core] perf tools: Simplify checking if SMT is active tip-bot2 for Konstantin Khlebnikov
2020-04-29 18:11 ` [PATCH v2 1/3] perf tool: fix reading new topology attribute "core_cpus" Arnaldo Carvalho de Melo
2020-05-08 13:05 ` [tip: perf/core] perf tools: Fix " tip-bot2 for Konstantin Khlebnikov
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