Date: Sat, 24 Nov 2007 22:24:50 -0800 From: Darren Reed <darrenr@freebsd.org> To: Max Laier <max@love2party.net> Cc: freebsd-net@freebsd.org, freebsd-current@freebsd.org, Robert Watson <rwatson@freebsd.org> Subject: Re: Switch pfil(9) to rmlocks Message-ID: <47491532.1050600@freebsd.org> In-Reply-To: <200711242006.04753.max@love2party.net> References: <200711231232.04447.max@love2party.net> <20071123132453.W98338@fledge.watson.org> <200711242006.04753.max@love2party.net>
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Max Laier wrote: > On Friday 23 November 2007, Robert Watson wrote: > > On Fri, 23 Nov 2007, Max Laier wrote: > > > attached is a diff to switch the pfil(9) subsystem to rmlocks, which > > > are more suited for the task. I'd like some exposure before doing > > > the switch, but I don't expect any fallout. This email is going > > > through the patched pfil already - twice. > > > > Max, > > > > Have you done performance measurements that show rmlocks to be a win in > > this scenario? I did some patchs for UNIX domain sockets to replace > > the rwlock there but it appeared not to have a measurable impact on SQL > > benchmarks, presumbaly because the read/write blend wasn't right and/or > > that wasnt a significant source of overhead in the benchmark. I'd > > anticipate a much more measurable improvement for pfil, but would be > > interested in learning how much is seen? > > I had to roll an artificial benchmark in order to see a significant change > (attached - it's a hack!). > > Using 3 threads on a 4 CPU machine I get the following results: > null hook: ~13% +/- 2 > mtx hook: up to 40% [*] > rw hook: ~5% +/- 1 > rm hook: ~35% +/- 5 > Is that 13%/5%/35% faster or slower or improvement or degradation? If "rw hook" (using rwlock like we have today?) is 5%, whas is the baseline? I'm expecting that at least one of these should be a 0%... Darren
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