From owner-freebsd-performance@FreeBSD.ORG Wed May 21 20:19:43 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 7933AE62; Wed, 21 May 2014 20:19:43 +0000 (UTC) Received: from melon.pingpong.net (melon.pingpong.net [79.136.116.200]) by mx1.freebsd.org (Postfix) with ESMTP id 3342B2BFE; Wed, 21 May 2014 20:19:42 +0000 (UTC) Received: from [10.19.39.26] (c-5eeaaaa2-74736162.cust.telenor.se [94.234.170.162]) (using TLSv1 with cipher AES128-SHA (128/128 bits)) (No client certificate requested) by melon.pingpong.net (Postfix) with ESMTPSA id 6896835C7F; Wed, 21 May 2014 22:19:40 +0200 (CEST) Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (1.0) Subject: Re: FreeBSD 10 and PostgreSQL 9.3 scalability issues From: Palle Girgensohn X-Mailer: iPhone Mail (11D201) In-Reply-To: Date: Wed, 21 May 2014 22:19:39 +0200 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: Sean Chittenden Cc: "freebsd-performance@freebsd.org" , Matthew Seaman 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 20:19:43 -0000 21 maj 2014 kl. 22:05 skrev Sean Chittenden : >>>> I did some tests with zfs, and results where appallingly bad, but that w= as 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 wa= s some time ago, maybe things have improved. >>> I have some hardware that I ran with last week wherein I was *not* able t= o reproduce any performance difference between ZFS and UFS2. On both UFS2 an= d ZFS I was seeing the same performance when using a a RAID10 / set of mirro= rs. I talked with the Dragonfly folk who originally performed these tests an= d they also saw the same thing: no real performance difference between ZFS a= nd UFS. I ran my tests on a host with 16 drive, 10K SAS, 192GB RAM. I also c= reated a kernel profiling image and ran the 20 concurrent user test under kg= prof(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 find= ings. The dfly methodology was observed when generating these results. Stay t= uned. -sc >>=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) I never meant that it was the core of our problem. Zfs vs ufs is out of scop= e here.=20 >=20 > When the working set fits in RAM (OS + PG), there isn't a performance diff= erence between 9.2 and 9.3. >=20 > 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 >=20 I don't agree. My original measurements showed a 20% slowdown for a reasonab= ly small ( -- > Sean Chittenden > sean@chittenden.org >=20 > _______________________________________________ > freebsd-performance@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-performance > To unsubscribe, send any mail to "freebsd-performance-unsubscribe@freebsd.= org"