From owner-freebsd-performance@FreeBSD.ORG Wed May 21 20:05:34 2014 Return-Path: Delivered-To: freebsd-performance@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id AF39E9B8; Wed, 21 May 2014 20:05:34 +0000 (UTC) Received: from mail01.lax1.stackjet.com (mon01.lax1.stackjet.com [174.136.104.178]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 886962AFB; Wed, 21 May 2014 20:05:33 +0000 (UTC) Received: from hormesis.group.on (localhost [127.0.0.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) (Authenticated sender: sean@chittenden.org) by mail01.lax1.stackjet.com (Postfix) with ESMTPSA id 488563E8DD8; Wed, 21 May 2014 13:05:30 -0700 (PDT) Received: from hormesis.group.on ([64.125.69.70] helo=hormesis.group.on) by ASSP.nospam with SMTPS(ECDHE-RSA-AES256-SHA)(ECDHE-RSA-AES256-SHA) (2.4.2); 21 May 2014 13:05:04 -0700 Content-Type: text/plain; charset=iso-8859-1 Mime-Version: 1.0 (Mac OS X Mail 7.3 \(1878.2\)) Subject: Re: FreeBSD 10 and PostgreSQL 9.3 scalability issues From: Sean Chittenden In-Reply-To: <537CEACD.8090701@FreeBSD.org> Date: Wed, 21 May 2014 13:05:30 -0700 Content-Transfer-Encoding: quoted-printable Message-Id: References: <5327B9B7.3050103@gmail.com> <2610F490C952470C9D15999550F67068@multiplay.co.uk> <532A192A.1070509@gmail.com> <572540F9-13E4-4BA9-88AE-5F47FB19450A@pingpong.net> <1BC3D447-2044-4AB8-B183-B83957BC9112@pingpong.net> <1473AF7C-B190-4CD4-B611-BA4090A081CB@pingpong.net> <537CEACD.8090701@FreeBSD.org> To: Matthew Seaman X-Mailer: Apple Mail (2.1878.2) X-Assp-Version: 2.4.2(14097) on ASSP.nospam X-Assp-ID: ASSP.nospam m1-02730-01908 X-Assp-Session: 842F2ADF8 (mail 1) X-Assp-Envelope-From: sean@chittenden.org X-Assp-Intended-For: matthew@FreeBSD.org X-Assp-Intended-For: freebsd-performance@freebsd.org X-Assp-Client-TLS: yes X-Assp-Server-TLS: yes Cc: freebsd-performance@freebsd.org X-BeenThere: freebsd-performance@freebsd.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: Performance/tuning List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 21 May 2014 20:05:34 -0000 >>> I did some tests with zfs, and results where appallingly bad, but = that was with db size > ram.=20 >>>>=20 >>>> I think the model used by PostgreSQL, as most databases, are very = disk block centric. Using zfs makes it hard to get good performance. But = this was some time ago, maybe things have improved.=20 >> I have some hardware that I ran with last week wherein I was *not* = able to reproduce any performance difference between ZFS and UFS2. On = both UFS2 and ZFS I was seeing the same performance when using a a = RAID10 / set of mirrors. I talked with the Dragonfly folk who originally = performed these tests and they also saw the same thing: no real = performance difference between ZFS and UFS. I ran my tests on a host = with 16 drive, 10K SAS, 192GB RAM. I also created a kernel profiling = image and ran the 20 concurrent user test under kgprof(1), dtrace, and = pmcstat and have the results available: >>=20 >> http://people.freebsd.org/~seanc/pg9.3-fbsd10-profiling/ >>=20 >> There are some investigations that are ongoing as a result of these = findings. The dfly methodology was observed when generating these = results. Stay tuned. -sc >>=20 >=20 > I'm not sure that the ZFS vs UFS2 question is at the core of the > performance problem. We're definitely seeing marked slowdowns between > Pg 9.2 and 9.3 on UFS2 (RAID10 + Dell H710p (mfi) raid controller with > 1GB NVRAM) When the working set fits in RAM (OS + PG), there isn't a performance = difference between 9.2 and 9.3. This is a good data point. I will try and reproduce this workload and = will run the performance profiling again to see if something else pops = up in the profiling. -sc -- Sean Chittenden sean@chittenden.org