Date: Thu, 22 Nov 2007 00:50:42 +0100 From: Max Laier <max@love2party.net> To: freebsd-stable@freebsd.org Cc: Attilio Rao <attilio@freebsd.org>, Kris Kennaway <kris@freebsd.org>, Alexey Popov <lol@chistydom.ru> Subject: Re: 2 x quad-core system is slower that 2 x dual core on FreeBSD Message-ID: <200711220050.51408.max@love2party.net> In-Reply-To: <4743629B.9090408@FreeBSD.org> References: <4741905E.8050300@chistydom.ru> <474339E9.4080301@FreeBSD.org> <4743629B.9090408@FreeBSD.org>
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[-- Attachment #1 --] On Tuesday 20 November 2007, Kris Kennaway wrote: > Kris Kennaway wrote: > > Kris Kennaway wrote: > >> In the meantime there is unfortunately not a lot that can be done, > >> AFAICT. There is one hack that I will send you later but it is not > >> likely to help much. I will also think about how to track down the > >> cause of the contention further (the profiling trace only shows that > >> it comes mostly from vget/vput but doesn't show where these are > >> called from). > > > > Actually this patch might help. It doesn't replace lockmgr but it > > does fix a silly thundering herd behaviour. It probably needs some > > adjustment to get it to apply cleanly (it is about 7 months old), and > > I apparently stopped using it because I ran into deadlocks. It might > > be stable enough to at least see how much it helps. > > > > Set the vfs.lookup_shared=1 sysctl to enable the other half of the > > patch. > > > > Kris > > Try this one instead, it applies to HEAD. You'll need to manually > enter the paths though because of how p4 mangles diffs. I rolled a tiny, simple, possibly braindamaged benchmark (but then again php code tends to be braindamaged): test.php includes 1000 different, essential empty files and is strated over and over from a shell script which counts the runs completed within 60seconds. 1-8,128 scripts are started in parallel. On a 2x dual Opteron running amd64 I get: stock RELENG_7 w/o patch ULE: jobs sum runs gain 1 617 1 2 784 1.27 3 939 1.52 4 1015 1.65 5 658 1.07 6 642 1.04 7 666 1.08 8 696 1.13 128 726 1.18 RELENG_7 patched ULE vfs.lookup_shared=1: jobs sum runs gain 1 637 1 2 784 1.23 3 973 1.53 4 1104 1.73 5 708 1.11 6 733 1.15 7 776 1.22 8 840 1.32 128 936 1.47 So there is still a lot of room for improvement here. I'll rebuild with lock profiling tomorrow and see what I can gather. Anything you'd like to see in particular? -- /"\ Best regards, | mlaier@freebsd.org \ / Max Laier | ICQ #67774661 X http://pf4freebsd.love2party.net/ | mlaier@EFnet / \ ASCII Ribbon Campaign | Against HTML Mail and News [-- Attachment #2 --] -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.4 (FreeBSD) iD8DBQBHRMRbXyyEoT62BG0RAnQOAJ9a3antCCJXeVi0kWWOR3nsrru2+ACfaz3T 0eED8jBN1DCMR2OqjtBOqzs= =y37s -----END PGP SIGNATURE-----
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