Date: Wed, 19 Mar 2014 16:33:10 -0700 From: Sean Chittenden <sean@chittenden.org> To: Petr Janda <janda.petr@gmail.com> Cc: freebsd-performance@freebsd.org, Steven Hartland <killing@multiplay.co.uk> Subject: Re: FreeBSD 10 and PostgreSQL 9.3 scalability issues Message-ID: <assp.0155c70d29.23ED6415-945D-4DF5-90DD-2F2CD7E198AF@chittenden.org> In-Reply-To: <532A192A.1070509@gmail.com> References: <5327B9B7.3050103@gmail.com> <2610F490C952470C9D15999550F67068@multiplay.co.uk> <532A192A.1070509@gmail.com>
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> As far as I know, the test was done on both UFS2 and ZFS and the > difference was marginal. As Adrian pointed out, there is an mmap(2) mutex in the way. Starting in = PostgreSQL 9.3, shared buffers are allocated out of mmap(2) instead of = shm. shm is only used to notify the PostgreSQL postmaster that a child = process exited/crashed (when a pid detaches from a shm segment, there is = a kernel event, but there is no kernel event when detaching from an = mmap(2) region). -sc http://www.postgresql.org/docs/9.3/static/release-9-3.html#AEN115039 >>> Just want to share these pgbench results done by DragonFlyBSD, and = would >>> like some input on why these numbers look so bad and what can be = done to >>> improve (ie. kernel tunables etc) the performance. >>>=20 >>> = http://lists.dragonflybsd.org/pipermail/users/attachments/20140310/4250b96= 1/attachment-0001.pdf >>>=20 >>=20 >>=20 >> Do you have the ability to test with FreeBSD 8.x and 9.x to see if = this is >> regression? >>=20 >> Also you don't mention the FS used in each case, so I'm wondering if = you >> used a ZFS install of FreeBSD which could help to explain things. -- Sean Chittenden sean@chittenden.org
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