Date: Tue, 04 Dec 2007 12:21:32 +0300 From: Alexey Popov <lol@chistydom.ru> To: Robert Watson <rwatson@FreeBSD.org> Cc: freebsd-stable@freebsd.org Subject: Re: 2 x quad-core system is slower that 2 x dual core on FreeBSD Message-ID: <47551C1C.3000903@chistydom.ru> In-Reply-To: <20071203163353.J79674@fledge.watson.org> References: <20071201213732.GA16638@cannabis.dataforce.net> <1497741406.20071201230441@rulez.sk> <20071202174540.GA29572@cannabis.dataforce.net> <200712020844.49718.linimon@FreeBSD.org> <4753C9E4.1060200@chistydom.ru> <20071203114037.G79674@fledge.watson.org> <47542372.3040303@chistydom.ru> <20071203163353.J79674@fledge.watson.org>
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Hi Robert Watson wrote: > Evidence in-hand seems to suggest that 8 core systems work very well for > most users, and reflect a significant performance increase with 7.0 over > previous FreeBSD releases. I disagree with that. Heavily loaded Apache, MySQL, Postgres does not work well. >>> The right path forwawrd at this point is to diagnosis the problems >>> and work on fixing them in 8-CURRENT, and assuming they are not >>> highly disruptive, MFC them for FreeBSD 7.1. >> >> I believe at least the bug with lockmgr contention should be fixed >> before release. > Could you point me at the specific proposed change in question? I don't > think I've seen it come across re@ as a potential merge request. > Changing locking primitives close to a release is, FYI, a risky > business, as while it may improve performance in specific cases, we may > not have a lot of information about more general cases. We also risk > opening up previously nascent race conditions in lock consumers. Kris sent me proof of concept patch that helped much against high lockmgr contention. After applying this patch 8-core server become faster that 4-core. But, again, it's still slower than Linux. Here's the patch: http://lists.freebsd.org/pipermail/freebsd-stable/2007-November/038449.html Here's Kris saying that it helps: http://lists.freebsd.org/pipermail/freebsd-stable/2007-November/038672.html I'm not sure it will help to MySQL and Prostgres, but symptoms are mostly identical. With best regards, Alexey Popov
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