Messages in this thread | | | Subject | Re: bisected: futex regression >= 3.14 - was - Slowdown due to threads bouncing between HT cores | From | Mike Galbraith <> | Date | Sun, 26 Oct 2014 14:16:15 +0100 |
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On Sun, 2014-10-26 at 11:39 +0100, Steinar H. Gunderson wrote: > On Fri, Oct 24, 2014 at 06:38:41PM +0200, Mike Galbraith wrote: > >>> Whew, good, futex.c is hard. Heads up chess guys <punt>. > >> I wonder whether the barrier fix which got into 3.17 late fixes that > >> issue as well. > > Yes, it did. > > This is only about the lockup, right, not that the threads bounce around a > lot and make things slower?
Yes. I couldn't reproduce your results, on my 28 core+ht box, there was little difference between pinned/unpinned. Maybe the box was too quite, not enough random activity to motivate select_idle_sibling().
-Mike
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