From 27db78307481dbba68c5f3563c6cb694b25521d9 Mon Sep 17 00:00:00 2001 From: Davidlohr Bueso Date: Sat, 14 Dec 2013 20:31:56 -0800 Subject: perf bench: Add futex-wake microbenchmark Block a bunch of threads on a futex and wake them up, N at a time. This program is particularly useful to measure the latency of nthread wakeups in non-error situations: all waiters are queued and all wake calls wakeup one or more tasks. An example run: $ perf bench futex wake -t 512 -r 100 Run summary [PID 27823]: blocking on 512 threads (at futex 0x7e10d4), waking up 1 at a time. [Run 1]: Wokeup 512 of 512 threads in 6.0080 ms [Run 2]: Wokeup 512 of 512 threads in 5.2280 ms [Run 3]: Wokeup 512 of 512 threads in 4.8300 ms ... [Run 100]: Wokeup 512 of 512 threads in 5.0100 ms Wokeup 512 of 512 threads in 5.0109 ms (+-2.25%) Signed-off-by: Davidlohr Bueso Acked-by: Darren Hart Cc: Aswin Chandramouleeswaran Cc: Darren Hart Cc: Ingo Molnar Cc: Jason Low Cc: Peter Zijlstra Cc: Scott J Norton Cc: Thomas Gleixner Cc: Waiman Long Link: http://lkml.kernel.org/r/1387081917-9102-3-git-send-email-davidlohr@hp.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/bench/futex.h | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'tools/perf/bench/futex.h') diff --git a/tools/perf/bench/futex.h b/tools/perf/bench/futex.h index 7d0bda543e3d..6ac45093fac4 100644 --- a/tools/perf/bench/futex.h +++ b/tools/perf/bench/futex.h @@ -45,4 +45,14 @@ futex_wait(u_int32_t *uaddr, u_int32_t val, struct timespec *timeout, int opflag return futex(uaddr, FUTEX_WAIT, val, timeout, NULL, 0, opflags); } +/** + * futex_wake() - wake one or more tasks blocked on uaddr + * @nr_wake: wake up to this many tasks + */ +static inline int +futex_wake(u_int32_t *uaddr, int nr_wake, int opflags) +{ + return futex(uaddr, FUTEX_WAKE, nr_wake, NULL, NULL, 0, opflags); +} + #endif /* _FUTEX_H */ -- cgit v1.2.3