Messages in this thread | | | Date | Thu, 2 Jul 2015 11:41:55 +0200 | From | Peter Zijlstra <> | Subject | Re: [RFC][PATCH 00/13] percpu rwsem -v2 |
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On Wed, Jul 01, 2015 at 02:54:59PM -0700, Linus Torvalds wrote: > On Tue, Jun 30, 2015 at 10:57 PM, Daniel Wagner <wagi@monom.org> wrote: > > > > And an attempt at visualization: > > > > http://monom.org/posix01/sweep-4.1.0-02756-ge3d06bd.png > > http://monom.org/posix01/sweep-4.1.0-02769-g6ce2591.png > > Ugh. The old numbers look (mostly) fairly tight, and then the new ones > are all over the map, and usually much worse. > > We've seen this behavior before when switching from a non-sleeping > lock to a sleeping one. The sleeping locks have absolutely horrible > behavior when they get contended, and spend tons of CPU time on the > sleep/wakeup management,
Right, I'm just not seeing how any of that would happen here :/ The read side would only ever block on reading /proc/$something and I'm fairly sure that benchmark doesn't actually touch that file.
In any case, I will look into this, I've just not had time yet..
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