Date: Mon, 03 May 2010 14:26:46 +0200 From: Giulio Ferro <auryn@zirakzigil.org> To: Jeremy Chadwick <freebsd@jdc.parodius.com>, freebsd-stable@freebsd.org Subject: Re: Freebsd 8.0 kmem map too small Message-ID: <4BDEC106.3040807@zirakzigil.org> In-Reply-To: <20100503110100.GA93137@icarus.home.lan> References: <4BDEA86E.3050109@zirakzigil.org> <20100503110100.GA93137@icarus.home.lan>
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On 03.05.2010 13:01, Jeremy Chadwick wrote: > On Mon, May 03, 2010 at 12:41:50PM +0200, Giulio Ferro wrote: > >> NFS server amd64 Freebsd 8.0 recent (2 days ago) >> >> This server has been running for several months without problems. >> Beginning last week, however, I'm experiencing panics (about 1 per day) >> with the error in the subject >> >> Current settings: >> >> >> vm.kmem_size_scale: 3 >> vm.kmem_size_max: 329853485875 >> vm.kmem_size_min: 0 >> vm.kmem_size: 2764046336 >> ... >> hw.physmem: 8568225792 >> hw.usermem: 6117404672 >> hw.realmem: 9395240960 >> ... >> vfs.zfs.l2arc_noprefetch: 0 >> vfs.zfs.l2arc_feed_secs_shift: 1 >> vfs.zfs.l2arc_feed_secs: 1 >> vfs.zfs.l2arc_headroom: 128 >> vfs.zfs.l2arc_write_boost: 67108864 >> vfs.zfs.l2arc_write_max: 67108864 >> vfs.zfs.arc_meta_limit: 431882240 >> vfs.zfs.arc_meta_used: 431874720 >> vfs.zfs.arc_min: 215941120 >> vfs.zfs.arc_max: 1727528960 >> >> >> I've set nothing in either /boot/loader.conf or sysctl.conf >> >> >> What should I do? >> > You need to adjust vm.kmem_size to provide more space for the ARC. > > Below are ZFS-relevant entries in our /boot/loader.conf on production > RELENG_8 systems with 8GB of RAM. The reason we set kmem_size to half > our physical system memory is because I didn't want to risk other > processes which use a larger maxdsiz/dfldsiz/maxssiz to potentially > exhaust all memory. > > > # Increase vm.kmem_size to allow for ZFS ARC to utilise more memory. > vm.kmem_size="4096M" > vfs.zfs.arc_max="3584M" > > # Disable ZFS prefetching > # http://southbrain.com/south/2008/04/the-nightmare-comes-slowly-zfs.html > # Increases overall speed of ZFS, but when disk flushing/writes occur, > # system is less responsive (due to extreme disk I/O). > # NOTE: 8.0-RC1 disables this by default on systems<= 4GB RAM anyway > # NOTE: System has 8GB of RAM, so prefetch would be enabled by default. > vfs.zfs.prefetch_disable="1" > > # Decrease ZFS txg timeout value from 30 (default) to 5 seconds. This > # should increase throughput and decrease the "bursty" stalls that > # happen during immense I/O with ZFS. > # http://lists.freebsd.org/pipermail/freebsd-fs/2009-December/007343.html > # http://lists.freebsd.org/pipermail/freebsd-fs/2009-December/007355.html > vfs.zfs.txg.timeout="5" > > > Thanks, I'll try these settings. I'll keep you posted.
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