From: Tommi Rantala <tommi.t.rantala@nokia.com>
To: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Tommi Rantala <tommi.t.rantala@nokia.com>,
Thomas Gleixner <tglx@linutronix.de>,
Darren Hart <dvhart@infradead.org>,
Mark Rutland <mark.rutland@arm.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
Davidlohr Bueso <dave@stgolabs.net>,
linux-kernel@vger.kernel.org
Subject: [PATCH 2/3] perf bench futex-wake: Restore thread count default to online CPU count
Date: Thu, 5 Mar 2020 10:37:13 +0200 [thread overview]
Message-ID: <20200305083714.9381-3-tommi.t.rantala@nokia.com> (raw)
In-Reply-To: <20200305083714.9381-1-tommi.t.rantala@nokia.com>
Since commit 3b2323c2c1c4 ("perf bench futex: Use cpumaps") the default
number of threads the benchmark uses got changed from number of online
CPUs to zero:
$ perf bench futex wake
# Running 'futex/wake' benchmark:
Run summary [PID 15930]: blocking on 0 threads (at [private] futex 0x558b8ee4bfac), waking up 1 at a time.
[Run 1]: Wokeup 0 of 0 threads in 0.0000 ms
[...]
[Run 10]: Wokeup 0 of 0 threads in 0.0000 ms
Wokeup 0 of 0 threads in 0.0004 ms (+-40.82%)
Restore the old behavior by grabbing the number of online CPUs via
cpu->nr:
$ perf bench futex wake
# Running 'futex/wake' benchmark:
Run summary [PID 18356]: blocking on 8 threads (at [private] futex 0xb3e62c), waking up 1 at a time.
[Run 1]: Wokeup 8 of 8 threads in 0.0260 ms
[...]
[Run 10]: Wokeup 8 of 8 threads in 0.0270 ms
Wokeup 8 of 8 threads in 0.0419 ms (+-24.35%)
Fixes: 3b2323c2c1c4 ("perf bench futex: Use cpumaps")
Signed-off-by: Tommi Rantala <tommi.t.rantala@nokia.com>
---
tools/perf/bench/futex-wake.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/tools/perf/bench/futex-wake.c b/tools/perf/bench/futex-wake.c
index df810096abfef..58906e9499bb0 100644
--- a/tools/perf/bench/futex-wake.c
+++ b/tools/perf/bench/futex-wake.c
@@ -43,7 +43,7 @@ static bool done = false, silent = false, fshared = false;
static pthread_mutex_t thread_lock;
static pthread_cond_t thread_parent, thread_worker;
static struct stats waketime_stats, wakeup_stats;
-static unsigned int ncpus, threads_starting, nthreads = 0;
+static unsigned int threads_starting, nthreads = 0;
static int futex_flag = 0;
static const struct option options[] = {
@@ -141,7 +141,7 @@ int bench_futex_wake(int argc, const char **argv)
sigaction(SIGINT, &act, NULL);
if (!nthreads)
- nthreads = ncpus;
+ nthreads = cpu->nr;
worker = calloc(nthreads, sizeof(*worker));
if (!worker)
--
2.21.1
next prev parent reply other threads:[~2020-03-05 8:37 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20200305083714.9381-1-tommi.t.rantala@nokia.com>
2020-03-05 8:37 ` [PATCH 1/3] perf top: Fix stdio interface input handling with glibc 2.28+ Tommi Rantala
2020-03-05 14:49 ` Arnaldo Carvalho de Melo
2020-03-06 7:47 ` Rantala, Tommi T. (Nokia - FI/Espoo)
2020-03-07 7:36 ` [tip: perf/urgent] " tip-bot2 for Tommi Rantala
2020-03-05 8:37 ` Tommi Rantala [this message]
2020-03-05 14:51 ` [PATCH 2/3] perf bench futex-wake: Restore thread count default to online CPU count Arnaldo Carvalho de Melo
2020-03-05 15:34 ` Davidlohr Bueso
2020-03-05 18:14 ` Arnaldo Melo
2020-03-07 7:36 ` [tip: perf/urgent] " tip-bot2 for Tommi Rantala
2020-03-05 8:37 ` [PATCH 3/3] perf bench: Clear struct sigaction before sigaction() syscall Tommi Rantala
2020-03-05 14:53 ` Arnaldo Carvalho de Melo
2020-03-07 7:36 ` [tip: perf/urgent] " tip-bot2 for Tommi Rantala
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