From owner-freebsd-performance@FreeBSD.ORG Tue Mar 18 12:16:46 2014 Return-Path: Delivered-To: freebsd-performance@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id AA0118C0; Tue, 18 Mar 2014 12:16:46 +0000 (UTC) Received: from mail-qa0-x230.google.com (mail-qa0-x230.google.com [IPv6:2607:f8b0:400d:c00::230]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (No client certificate requested) by mx1.freebsd.org (Postfix) with ESMTPS id 5B9967B2; Tue, 18 Mar 2014 12:16:46 +0000 (UTC) Received: by mail-qa0-f48.google.com with SMTP id m5so6714690qaj.7 for ; Tue, 18 Mar 2014 05:16:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:sender:in-reply-to:references:date:message-id:subject :from:to:cc:content-type; bh=jOa7NUWuqIg+9uk93t90+i339uodPNU7vp9Gp637Dt0=; b=GmVQ4FnehVrXZahldBQDP8n5pl8monwHIPbKkv8M59UGWy2ENXdutEQZLnXBrLo/bF YYy+PrM8hDyAbgZdSX81fwCu1BMbn13XhEs3L+pftrt16SRAigSTUeqZU02178ZVa9XR 8G+v/YvHTuVIvNdQtFU/0yt5P53h4VgtYnHIi7LNGumbEIMB7DW6J6X5vA4gPZP3Cqgf k+WitgNGsARAy4YQz1rBlPDn1byGl+msw6EAimYt5SViaq1E39emWuPH09SKneemPb4b 1XawwH2xqDOQxvQXWU9k0Ictq7xTzCaKmbr91pzAwsrbmuO7MoCLiQLSQeHVXCkT4ay3 JBaw== MIME-Version: 1.0 X-Received: by 10.224.29.4 with SMTP id o4mr13517328qac.55.1395145005556; Tue, 18 Mar 2014 05:16:45 -0700 (PDT) Sender: adrian.chadd@gmail.com Received: by 10.224.8.137 with HTTP; Tue, 18 Mar 2014 05:16:44 -0700 (PDT) In-Reply-To: <53283557.4070105@freebsd.org> References: <5327B9B7.3050103@gmail.com> <53283557.4070105@freebsd.org> Date: Tue, 18 Mar 2014 05:16:44 -0700 X-Google-Sender-Auth: C9rZDHuz_SsYVQ5V2cGtck4Duuo Message-ID: Subject: Re: FreeBSD 10 and PostgreSQL 9.3 scalability issues From: Adrian Chadd To: Matthew Seaman Content-Type: text/plain; charset=ISO-8859-1 Cc: FreeBSD Mailing Lists X-BeenThere: freebsd-performance@freebsd.org X-Mailman-Version: 2.1.17 Precedence: list List-Id: Performance/tuning List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 18 Mar 2014 12:16:46 -0000 Hi, the pgsql testing done has been analysed by a few developers. The TL;DR version is that there's significant lock contention in the VM / mmap path and it sticks out like a sore thumb when one does lock profiling. -a On 18 March 2014 05:00, Matthew Seaman wrote: > On 03/18/14 03:12, Petr Janda wrote: >> ust 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. >> >> http://lists.dragonflybsd.org/pipermail/users/attachments/20140310/4250b961/attachment-0001.pdf > > Using ZFS as the backing for a RDBMS without: > > * Separate (fast) L2ARC devices > * Tuning the ZFS block size to match the postgres IO block size > * Setting primarycache to metadata > * Tuning the ARC max so ZFS doesn't eat all the RAM > * probably other things I can remember off-hand. > > That's what is wrong. ZFS is known to work particularly badly at the > sort of small random IOs that RDBMSes generate (mostly because of the > copy-on-write thing) without special tuning and extra hardware for > caches. ie. You can't construct a fair test of database performance > against other OSes/filesystems if you restrict yourself to using exactly > the same hardware. > > Basically, install the FreeBSD box on UFS2 and try again. > > Cheers, > > Matthew > >