• Davidlohr Bueso's avatar
    perf bench: Add futex-wake microbenchmark · 27db7830
    Davidlohr Bueso authored
    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: default avatarDavidlohr Bueso <davidlohr@hp.com>
    Acked-by: default avatarDarren Hart <dvhart@linux.intel.com>
    Cc: Aswin Chandramouleeswaran <aswin@hp.com>
    Cc: Darren Hart <dvhart@linux.intel.com>
    Cc: Ingo Molnar <mingo@redhat.com>
    Cc: Jason Low <jason.low2@hp.com>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Scott J Norton <scott.norton@hp.com>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: Waiman Long <Waiman.Long@hp.com>
    Link: http://lkml.kernel.org/r/1387081917-9102-3-git-send-email-davidlohr@hp.comSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
    27db7830
futex-wake.c 5.26 KB