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

Kris Kennaway kris at
Tue May 9 00:43:40 UTC 2006

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.

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