Fine-grained locking for POSIX local sockets (UNIX domain sockets)

Kris Kennaway kris at
Tue May 9 01:21:07 UTC 2006

On Mon, May 08, 2006 at 06:18:18PM -0700, Maxim Sobolev wrote:
> Kris Kennaway wrote:
> >On Mon, May 08, 2006 at 02:52:07AM -0400, Kris Kennaway wrote:
> >>OK, David's patch fixes the umtx thundering herd (and seems to give a
> >>4-6% boost).  I also fixed a thundering herd in FILEDESC_UNLOCK (which
> >>was also waking up 2-7 CPUs at once about 30% of the time) by doing
> >>s/wakeup/wakeup_one/.  This did not seem to give a performance impact
> >>on this test though.
> >
> >Turning down kern.hz from 1000 to 100 also made a big difference on 12
> >CPUs (+6.1%).
> >
> >Note also that the system is no less than 40% idle during the runs (at
> >any load), so the bottlenecks are serious.
> Maybe HDD just can't keep up with the pace?

There is no disk I/O involved.

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