On Sunday 25 November 2007, Darren Reed wrote: > 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%... Sorry for the sparse explanation. All numbers above are gain with rmlocks i.e. rmlocks are faster in all scenarios. The test cases are different hook functions. Every hook has a DELAY(1) and a lock/unlock call around it of the respective lock type. read lock acquisitions for rw and rm. Please look at the code I posted a bit later for more details. -- /"\ Best regards, | mlaier_at_freebsd.org \ / Max Laier | ICQ #67774661 X http://pf4freebsd.love2party.net/ | mlaier_at_EFnet / \ ASCII Ribbon Campaign | Against HTML Mail and News
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