Date: Thu, 29 Apr 2010 11:25:46 -0700 From: Artem Belevich <fbsdlist@src.cx> To: Scott Long <scottl@samsco.org> Cc: Tom Evans <tevans.uk@googlemail.com>, Ollivier Robert <roberto@keltia.freenix.fr>, freebsd-current@freebsd.org Subject: Re: kmem_map too small: 3832475648 total allocated Message-ID: <g2qed91d4a81004291125w31fce07bq53c5feab1fe28980@mail.gmail.com> In-Reply-To: <E79134A9-2174-4905-85A6-ADAEC0EA7D66@samsco.org> References: <4BD8F7FA.2080103@jrv.org> <20100429145334.GB62822@roberto-al.eurocontrol.fr> <n2m2e027be01004290844k51dd6060q77375e894ff4efc4@mail.gmail.com> <E79134A9-2174-4905-85A6-ADAEC0EA7D66@samsco.org>
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If I understand it correctly, the problem in this case is that even when you do have more than enough RAM, kernel just does not provide enough space in kmem_map to map that physical memory into. Unless you want to have dedupe turned on large filesystem (and FreeBSD does not have this feature yet), you don't really *need* all that much RAM. "kmem_map too small" comes up as an issue way more often than lack of physical memory. --Artem On Thu, Apr 29, 2010 at 9:56 AM, Scott Long <scottl@samsco.org> wrote: > On Apr 29, 2010, at 9:44 AM, Tom Evans wrote: >> On Thu, Apr 29, 2010 at 3:53 PM, Ollivier Robert >> <roberto@keltia.freenix.fr> wrote: >>> According to James R. Van Artsdalen: >>>> system is a Core i7 975 (3.33 GHz x 4 cores 3x threads per core) with = 12 >>>> GB of RAM, a 2x2TB ZFS boot pool and a second (idle) pool of 16x2TB. >>> >>>> panic: kmem_malloc(131072): kmem_map too small: 3832475648 total alloc= ated >>> >>> Apart from the fact that you must at least set vm.kmem_size to somethin= g like 2x your RAM, one rule of thumb I've seen discussed for ZFS is that y= ou will need approximatively 1 GB of RAM per TB of data so you may be a bit= short here to get optimal perfs. >>> >> >> Citation needed? I have a file server running amd64 8-STABLE with 4GB >> of RAM, 6 x 1.5 TB drives in raidz, and have never had any problems >> with memory usage. Are you saying that after my next update, adding >> another 6 x 1.5 TB drives, it will start being flaky and/or panicing >> with kmem_map too small errors? >> > > I'm sorry, but I find it absolutely absurd that any filesystem has to wir= e down 2GB of RAM, and that the solution to panics is buy more RAM. > > Scott > > _______________________________________________ > freebsd-current@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-current > To unsubscribe, send any mail to "freebsd-current-unsubscribe@freebsd.org= " >
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