From owner-freebsd-stable@FreeBSD.ORG Mon Apr 13 02:43:28 2009 Return-Path: Delivered-To: freebsd-stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 64319106566C; Mon, 13 Apr 2009 02:43:28 +0000 (UTC) (envelope-from ben@wanderview.com) Received: from mail.wanderview.com (mail.wanderview.com [66.92.166.102]) by mx1.freebsd.org (Postfix) with ESMTP id D238D8FC1A; Mon, 13 Apr 2009 02:43:27 +0000 (UTC) (envelope-from ben@wanderview.com) Received: from harkness.in.wanderview.com (harkness.in.wanderview.com [10.76.10.150]) (authenticated bits=0) by mail.wanderview.com (8.14.3/8.14.3) with ESMTP id n3D2MNLg024867 (version=TLSv1/SSLv3 cipher=AES128-SHA bits=128 verify=NO); Mon, 13 Apr 2009 02:22:24 GMT (envelope-from ben@wanderview.com) Message-Id: <52250990-6DD5-4FCE-8804-59D0B17D6790@wanderview.com> From: Ben Kelly To: Christian Walther In-Reply-To: <14989d6e0904080918l78d6e52eja46d7dd258b1659a@mail.gmail.com> Content-Type: text/plain; charset=US-ASCII; format=flowed; delsp=yes Content-Transfer-Encoding: 7bit Mime-Version: 1.0 (Apple Message framework v930.3) Date: Sun, 12 Apr 2009 22:22:22 -0400 References: <14989d6e0904080918l78d6e52eja46d7dd258b1659a@mail.gmail.com> X-Mailer: Apple Mail (2.930.3) X-Spam-Score: -1.44 () ALL_TRUSTED X-Scanned-By: MIMEDefang 2.64 on 10.76.20.1 Cc: freebsd-stable@freebsd.org, Ivan Voras Subject: Re: ZFSKnownProblems - needs revision? X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 13 Apr 2009 02:43:28 -0000 On Apr 8, 2009, at 12:18 PM, Christian Walther wrote: > I used geli encrypted ZFS including Root on my IBM Thinkpad T31 with > 1GB RAM on a 160GB HDD. (i386 7-STABLE) > Swap on a dedicated slice. Some Z Filesystems used compression > (/usr/ports, /usr/src, for example). > > I encountered several crashes, especially during heavy loads, such as > compiling big ports. Can you clarify what you mean by "crashes"? I have a very similar system here using zfs on geli with compression on a non-SMP i386 machine. The only real difference is that I am running 8-CURRENT. With this setup I've found that I can reliably get the system to go into livelock under load. I posted some analysis and a possible patch in this thread: http://docs.freebsd.org/cgi/getmsg.cgi?fetch=832196+0+archive/2009/freebsd-current/20090322.freebsd-current I'm still investigating what exactly triggers the problem, but it appears that if the ARC cache comes under memory pressure at the wrong time certain zfs transaction threads can enter an interlocked looping pattern. Without proper thread prioritization this can prevent the system from writing data out and thus keep the loop running forever. You can find a better copy of the patch here: http://www.wanderview.com/svn/public/misc/zfs_livelock/zfs_thread_priority.diff I intend to update this with some tweaked priority values, but this should still work fine. Please note, however, that at least one person encountered a panic when they tried this patch. Its not clear if this was due to the thread priority changes interacting with their zfs-on-root configuration or if it was unrelated 8-CURRENT changes. Also, I have not tested the patch against 7-STABLE. I'd be interested to know if it helps with your systems (although it sounds like you abandoned zfs already). Anyway, I hope that helps. - Ben