Date: Sun, 12 Apr 2009 22:22:22 -0400 From: Ben Kelly <ben@wanderview.com> To: Christian Walther <cptsalek@gmail.com> Cc: freebsd-stable@freebsd.org, Ivan Voras <ivoras@freebsd.org> Subject: Re: ZFSKnownProblems - needs revision? Message-ID: <52250990-6DD5-4FCE-8804-59D0B17D6790@wanderview.com> In-Reply-To: <14989d6e0904080918l78d6e52eja46d7dd258b1659a@mail.gmail.com> References: <gri5d9$15l$1@ger.gmane.org> <14989d6e0904080918l78d6e52eja46d7dd258b1659a@mail.gmail.com>
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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
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