Messages in this thread | | | Subject | Re: Scheduler(?) regression from 2.6.22 to 2.6.24 for short-lived threads | From | Mike Galbraith <> | Date | Mon, 11 Feb 2008 20:58:46 +0100 |
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On Mon, 2008-02-11 at 11:26 -0600, Olof Johansson wrote: > On Mon, Feb 11, 2008 at 09:15:55AM +0100, Mike Galbraith wrote: > > Piddling around with your testcase, it still looks to me like things > > improved considerably in latest greatest git. Hopefully that means > > happiness is in the pipe for the real workload... synthetic load is > > definitely happier here as burst is shortened. > > The real workload doesn't see much of an improvement. The changes I did > when tinkering yesterday seem like they're better at modelling just > what's going on with that one.
So the real application is trying to yield? If so, you could try prodding /proc/sys/kernel/sched_compat_yield.
It shouldn't matter if you yield or not really, that should reduce the number of non-work spin cycles wasted awaiting preemption as threads execute in series (the problem), and should improve your performance numbers, but not beyond single threaded.
If I plugged a yield into the busy wait, I would expect to see a large behavioral difference due to yield implementation changes, but that would only be a symptom in this case, no? Yield should be a noop.
-Mike
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