Re: Network slowdown due to CFS

From: Ingo Molnar
Date: Wed Sep 26 2007 - 07:22:02 EST

* Martin Michlmayr <tbm@xxxxxxxxxx> wrote:

> * Mike Galbraith <efault@xxxxxx> [2007-09-26 12:23]:
> > I noticed on the iperf website a patch which contains sched_yield().
> >
> >
> > Do you have that patch applied by any chance? If so, it might be a
> > worth while to try it without it.
> Yes, this patch was applied. When I revert it, I get the same (high)
> performance with both kernels.

great! Could you try this too:

echo 1 > /proc/sys/kernel/sched_compat_yield

does it fix iperf performance too (with the yield patch applied to

I think the real fix would be for iperf to use blocking network IO
though, or maybe to use a POSIX mutex or POSIX semaphores.

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