Date: Wed, 13 Jan 2010 13:21:52 -0600 From: "Doug Poland" <doug@polands.org> To: "Ivan Voras" <ivoras@freebsd.org> Cc: Doug Poland <doug@polands.org>, freebsd-questions@freebsd.org Subject: Re: 8.0-R-p2 ZFS: unixbench causing kmem exhaustion panic Message-ID: <b41ca31fbeacf104143509e8cba2fe66.squirrel@email.polands.org> In-Reply-To: <9bbcef731001131035x604cdea1t81b14589cb10ad25@mail.gmail.com> References: <8418112cdfada93d83ca0cb5307c1d21.squirrel@email.polands.org> <hil1e8$ebs$1@ger.gmane.org> <b78f9b16683331ad0f574ecfc1b7f995.squirrel@email.polands.org> <9bbcef731001131035x604cdea1t81b14589cb10ad25@mail.gmail.com>
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On Wed, January 13, 2010 12:35, Ivan Voras wrote: >>> >>> Try adding vfs.zfs.arc_max=512M to /boot/loader.conf. >>> >> Would you suggest tweaking the vm.kmem_size tunables in addition to >> arc_max? > > No, unless they auto-tune to something lesser than approximately > arc_max*3. > > I try to set arc_max to be a third (or a quarter) the kmem_size, and > tune kmem_size ad_hoc to suit the machine and its purpose. > > The reason for this is that "arc_max" is just a guideline, not a hard > limit... the ZFS ARC usage can and will spike to much larger values, > usually in the most inopportune moment. > This is the state of the machine when it panicked this time: panic: kmem_malloc(131072): kmem_map too small: 1296957440 total allocated cpuid = 1 /boot/loader.conf: vfs.zfs.arc_max=512M vfs.numvnodes: 660 vfs.zfs.arc_max: 536870912 vfs.zfs.arc_meta_limit: 134217728 vfs.zfs.arc_meta_used: 7006136 vfs.zfs.arc_min: 67108864 vfs.zfs.zil_disable: 0 vm.kmem_size: 1327202304 vm.kmem_size_max: 329853485875 Using a handy little script I found posted in several places, I was monitoring memory: TEXT 15373968 14.66 MiB DATA 1536957440 1465.76 MiB TOTAL 1552331408 1480.42 MiB Where TEXT = a sum of kldstat memory values and DATA = a sum of vmstat -m values Is there a next step to try, or is this chasing a wild goose? -- Regards, Doug
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