From owner-freebsd-current@FreeBSD.ORG Fri Apr 17 06:43:31 2009 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id F0DBE1065672 for ; Fri, 17 Apr 2009 06:43:31 +0000 (UTC) (envelope-from ken@mthelicon.com) Received: from hercules.mthelicon.com (hercules.mthelicon.com [IPv6:2001:49f0:2023::2]) by mx1.freebsd.org (Postfix) with ESMTP id C114C8FC0A for ; Fri, 17 Apr 2009 06:43:31 +0000 (UTC) (envelope-from ken@mthelicon.com) Received: from feathers.peganest.com (feathers.peganest.com [78.33.110.3]) (authenticated bits=0) by hercules.mthelicon.com (8.14.3/8.14.3) with ESMTP id n3H6hTuR021014 (version=TLSv1/SSLv3 cipher=DHE-DSS-AES256-SHA bits=256 verify=NO) for ; Fri, 17 Apr 2009 06:43:30 GMT (envelope-from ken@mthelicon.com) From: Pegasus Mc Cleaft Organization: Feathers To: freebsd-current@freebsd.org Date: Fri, 17 Apr 2009 06:43:28 +0000 User-Agent: KMail/1.11.2 (FreeBSD/8.0-CURRENT; KDE/4.2.2; amd64; ; ) References: <7DEF7288-1304-4A64-8A23-BB03349653EA@wanderview.com> In-Reply-To: <7DEF7288-1304-4A64-8A23-BB03349653EA@wanderview.com> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200904170643.28862.ken@mthelicon.com> Subject: Re: [patch] zfs livelock and thread priorities X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 17 Apr 2009 06:43:32 -0000 On Friday 17 April 2009 01:30:21 Ben Kelly wrote: > On Apr 15, 2009, at 12:35 AM, Artem Belevich wrote: > > I'll give it a try in a few days. I'll let you know how it went. > > Just FYI, I was able to reproduce some of the failures with the > original patch using an SMP vmware image. The new patch seems to fix > these problems and I was able to successfully mount a zfs pool. > > > BTW, now that you're tinkering with ZFS threads and priorities, whould > > you by any chance have any idea why zfs scrub is so painfully slow on > > -current? > > When I start scrub on my -stable box, it pretty much runs full speed > > -- I can see disks under load all the time. > > However on -current scrub seems to run in small bursts. Disks get busy > > for a second or so and then things get quiet for about five seconds or > > so and this pattern repeats over and over. > > I don't know. I haven't had to scrub my devices very often. I ran a > couple here locally and did not see the behavior you describe. There > is a significant delay between typing zpool scrub and when it actually > begins disk I/O, but after that it completes without pause. If I get > a chance I'll try to look at what the scrub code is doing. Hi Ben, I saw the same pausing of of a scrub on my machine as Artem is. It may be coincidence, but I had disabled the zil and prefetch. After I re-enabled the zil and prefetch, the pausing stopped and the scrub would complete without any stalling. I never disabled the zil and prefetch to see if this was the true cause or not.. Peg