Messages in this thread |  | | | Subject | Re: slow nanosleep? | | From | Peter Zijlstra <> | | Date | Wed, 08 Sep 2010 15:00:18 +0200 |
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On Wed, 2010-09-08 at 14:43 +0200, Thomas Gleixner wrote: > > However nanosleep with 1 ns and prctl(PR_SET_TIMERSLACK, 1) takes > > about 8 us on x86(Intel(R) Core(TM)2 Duo CPU E8500 @ 3.16GHz) > > and 20 us on my slower ppc board. Is that system call overhead > > or possibly some error? > > That's overhead I fear. We go way up to enqueue/arm the timer until we > figure out that the timeout already happened.
Well, there's also the fact that his ppc board is simply dead slow, using the freq ratio: 3166/266 you'd expect (at a similar ins/clock ratio) the ppc to take 95us.
So in fact the pcc taking 20us is actually quite good.
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