Date: Tue, 14 Apr 2009 11:50:18 -0400 From: Ben Kelly <ben@wanderview.com> To: Artem Belevich <fbsdlist@src.cx> Cc: freebsd-current@freebsd.org Subject: Re: [patch] zfs livelock and thread priorities Message-ID: <08D7DC2A-68BE-47B6-8D5D-5DE6B48F87E5@wanderview.com> In-Reply-To: <ed91d4a80904131636u18c90474w7cdaa57bc7000e02@mail.gmail.com> References: <DC9F2088-A0AF-467D-8574-F24A045ABD81@wanderview.com> <49C2CFF6.8070608@egr.msu.edu> <BDABA909-C2AE-4A55-869B-CA01BE778A82@wanderview.com> <ed91d4a80904131636u18c90474w7cdaa57bc7000e02@mail.gmail.com>
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On Apr 13, 2009, at 7:36 PM, Artem Belevich wrote:
> Tried your patch that used PRIBIO+{1,2} for priorities with -current
> r191008 and the kernel died with "spinlock held too long" panic.
> Actually, there apparently were two instances of panic on different
> cores..
>
> Here's output of "alltrace" and "ps" after the crash:
> http://pastebin.com/f140f4596
>
> I've reverted the change and kernel booted just fine.
>
> The box is quad-core with two ZFS pools -- one single-disk and another
> one is a two-disk mirror. Freebsd is installed on UFS partitions, ZFS
> is used for user stuff only.
Thanks for the report!
I don't have a lot of time to look at this today, but it appears that
there is a race condition on SMP machines when setting the priority
immediately after the kproc is spawned. As a quick hack I tried
adding a pause between the kproc_create() and the sched_prio(). Can
you try this patch?
http://www.wanderview.com/svn/public/misc/zfs_livelock/zfs_thread_priority.diff
I'll try to take a closer look at this later in the week.
Thanks!
- Ben
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