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Date:      Mon, 8 May 2006 20:43:28 -0400
From:      Kris Kennaway <kris@obsecurity.org>
To:        Kris Kennaway <kris@obsecurity.org>
Cc:        performance@FreeBSD.org, Robert Watson <rwatson@FreeBSD.org>, current@FreeBSD.org
Subject:   Re: Fine-grained locking for POSIX local sockets (UNIX domain sockets)
Message-ID:  <20060509004328.GB55852@xor.obsecurity.org>
In-Reply-To: <20060508065207.GA20386@xor.obsecurity.org>
References:  <20060506150622.C17611@fledge.watson.org> <20060506221908.GB51268@xor.obsecurity.org> <20060507210426.GA4422@xor.obsecurity.org> <20060507214153.GA5275@xor.obsecurity.org> <20060507230430.GA6872@xor.obsecurity.org> <20060508065207.GA20386@xor.obsecurity.org>

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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.

Kris

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