Date: Tue, 09 Oct 2007 12:41:21 -0700 From: Darren Reed <darrenr@freebsd.org> To: Pawel Jakub Dawidek <pjd@FreeBSD.org> Cc: freebsd-fs@FreeBSD.org, freebsd-current@FreeBSD.org Subject: Re: ZFS kmem_map too small. Message-ID: <470BD961.4000407@freebsd.org> In-Reply-To: <20071008121523.GM2327@garage.freebsd.pl> References: <20071005000046.GC92272@garage.freebsd.pl> <20071008121523.GM2327@garage.freebsd.pl>
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Pawel Jakub Dawidek wrote: > Here are some updates: > > I was able to reproduce the panic by rsyncing big files and trying > bonnie++ test suggested in this thread. > > Can you guys retry with this patch: > > http://people.freebsd.org/~pjd/patches/vm_kern.c.2.patch > So, I have a question... What happens if the "for (i = 0..)" is changed to "while(1)" and the "panic" is subsequently removed? It appears like the code changes the meaning of "WAIT" to "wait for 4 seconds" then panic if it won't work. Previously, "WAIT" was not waiting at all...whch could be described as a bug! If I recall correctly, ZFS caches writes and doe them in spurts and that those spurts are spaced out more than 4 seconds. (For the curious, do "zpool status" and observe the gap in time between write activity.) If you start a large amount of I/O, it is possible that all the KVA will be used up and ZFS will not get a chance to flush its buffers before the 4s timer here expires. Does that sound plausible? Would doubling the 8 to (say) 16 be beneficial here, to at least make the waiting span one ZFS flush out to disk? Darren
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