Date: Sat, 3 Oct 2009 02:09:09 +0200 From: Pawel Jakub Dawidek <pjd@FreeBSD.org> To: Artem Belevich <fbsdlist@src.cx> Cc: freebsd-fs@freebsd.org Subject: Re: ARC size constantly shrinks, then ZFS slows down extremely Message-ID: <20091003000909.GD1660@garage.freebsd.pl> In-Reply-To: <ed91d4a80910021638r72213389uf0767b9bb523b7d9@mail.gmail.com> References: <4AC1E540.9070001@fsn.hu> <4AC5B2C7.2000200@fsn.hu> <20091002184526.GA1660@garage.freebsd.pl> <ed91d4a80910021638r72213389uf0767b9bb523b7d9@mail.gmail.com>
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[-- Attachment #1 --] On Fri, Oct 02, 2009 at 04:38:24PM -0700, Artem Belevich wrote: > With the patch, if vfs.zfs.arc_min is set high enough, the system locks up. > > On a box with 8G or RAM I had arc_min=6G and arc_max=7G. Once ARC grew > to ~5.8G as reported by kstat.zfs.misc.arcstats.size, number of wired > pages grew to ~7400MB and the processes got stuck in 'vmwait' state. I > had to reboot in order to recover. > > On one hand setting arc_min can be considered a pilot error. On the > other, it may be a good idea to allow system to reclaim memory from > ARC even if ARC is smaller than arc_min if the system really really > needs it. The question is how to define "really needs it". > > On a side note, it appears that wired page count tends to be > substantially larger than ARC size. I.e. in my case if ARC size grows > to 6G, wired page count is about 1.5G bigger. Perhaps we should allow > reclaiming memory Before we start debuging pathological cases, could you try the patch with defaul settings? Eventually with vm.kmem_size set to the amount of RAM you have. -- Pawel Jakub Dawidek http://www.wheel.pl pjd@FreeBSD.org http://www.FreeBSD.org FreeBSD committer Am I Evil? Yes, I Am! [-- Attachment #2 --] -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.4 (FreeBSD) iD8DBQFKxpYlForvXbEpPzQRAonOAKDraj7ZSbTaC/31Up5xzjDd0HIfLACgpf4m WdRgq+8TSAI2nvZbbQKMg2c= =Ur6x -----END PGP SIGNATURE-----
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