Date: Mon, 03 Feb 2014 12:02:39 +0700 From: Eugene Grosbein <eugen@grosbein.net> To: Matthew Rezny <matthew@reztek.cz> Cc: freebsd-stable@freebsd.org Subject: Re: Tuning kern.maxswzone is minor compared to hangs in "kmem a" state Message-ID: <52EF22EF.8010902@grosbein.net> In-Reply-To: <20140202204623.00003fe5@unknown> References: <20140201070912.00007971@unknown> <x7d2j64pvw.fsf@ichotolot.servalan.com> <20140201221612.00001897@unknown> <20140202204623.00003fe5@unknown>
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On 03.02.2014 02:46, Matthew Rezny wrote: > Just as I was about to hit send, the box panicked. Finally a panic and > not just a hang so there's a backtrace! That should be the first hint > as to where in the kernel I'm hitting trouble. The panic points the > finger at UFS. The filesystem has seen some thrashing but it did just > fsck without significant error before that build was started. So, I'm > thinking it's not on-disk corruption but an in-memory problem. It blew > up writing a softdep, which starts me wondering if the buffers used for > softupdates bookkeeping are overflowing in the kernel. That would make > some sense, rapidly creating (svn/tar) or deleting (rm) many small > files will create a huge amount of activity for softupdates to track, > defer and reorder. The rm case is probably the one than can trigger it > the fastest because deletes are focusing the beating on the metadata > without wasting time between on file data I/O. See also http://www.freebsd.org/cgi/query-pr.cgi?pr=kern/176857
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