From owner-freebsd-fs@FreeBSD.ORG Thu Dec 31 22:37:06 2009 Return-Path: Delivered-To: freebsd-fs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id A5D91106566C for ; Thu, 31 Dec 2009 22:37:06 +0000 (UTC) (envelope-from bfriesen@simple.dallas.tx.us) Received: from blade.simplesystems.org (blade.simplesystems.org [65.66.246.74]) by mx1.freebsd.org (Postfix) with ESMTP id 69AC88FC08 for ; Thu, 31 Dec 2009 22:37:06 +0000 (UTC) Received: from freddy.simplesystems.org (freddy.simplesystems.org [65.66.246.65]) by blade.simplesystems.org (8.13.8+Sun/8.13.8) with ESMTP id nBVMarbm011123; Thu, 31 Dec 2009 16:36:53 -0600 (CST) Date: Thu, 31 Dec 2009 16:36:53 -0600 (CST) From: Bob Friesenhahn X-X-Sender: bfriesen@freddy.simplesystems.org To: jhell In-Reply-To: Message-ID: References: User-Agent: Alpine 2.01 (GSO 1266 2009-07-14) MIME-Version: 1.0 Content-Type: MULTIPART/MIXED; BOUNDARY="-559023410-76287759-1262299013=:1586" X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.2 (blade.simplesystems.org [65.66.246.90]); Thu, 31 Dec 2009 16:36:53 -0600 (CST) Cc: freebsd-fs@freebsd.org Subject: Re: ZFS prefetch problem X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 31 Dec 2009 22:37:06 -0000 This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. ---559023410-76287759-1262299013=:1586 Content-Type: TEXT/PLAIN; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 8BIT On Thu, 31 Dec 2009, jhell wrote: >> >> looks good. >> tested on 8-STABLE amd64, with/without log/cache ssd. (but not with >> zil_disable) >> > > Thanks for the heads up on this. I have applied the following to a stable/7 > system @r201336 "The obrien new year copyright ;)" and will write back with > further results. Now if someone can figure out how to crank up (double) the prefetch rate for my little test, I would be happy. 145MB/second is not nearly enough, especially if zfs can sometimes deliver 5X (or more) that rate. The read performance I see here (under Solaris 10) is very similar to the numbers posted by Mickaël Maillot. In fact initial read performance values posted by many others was almost the same, regardless of how many drives are available (e.g. 2 or 48 SAS drives). This suggests that zfs is not accellerating prefetch fast enough to make much difference for 8GB files. Bob -- Bob Friesenhahn bfriesen@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/ GraphicsMagick Maintainer, http://www.GraphicsMagick.org/ ---559023410-76287759-1262299013=:1586--