Date: Tue, 29 Jul 2008 10:29:48 +1000 From: Antony Mawer <fbsd-fs@mawer.org> To: Ivan Voras <ivoras@freebsd.org> Cc: freebsd-fs@freebsd.org, freebsd-current@freebsd.org Subject: Re: ZFS patches. Message-ID: <488E647C.7@mawer.org> In-Reply-To: <g6ln6j$c7k$2@ger.gmane.org> References: <20080727125413.GG1345@garage.freebsd.pl> <g6ln6j$c7k$2@ger.gmane.org>
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Ivan Voras wrote: > Pawel Jakub Dawidek wrote: >> Hi. >> >> http://people.freebsd.org/~pjd/patches/zfs_20080727.patch.bz2 >> >> The patch above contains the most recent ZFS version that could be found >> in OpenSolaris as of today. Apart for large amount of new functionality, >> I belive there are many stability (and also performance) improvements >> compared to the version from the base system. >> >> Check out OpenSolaris website to find out the differences between base >> system version and patch version. >> >> Please test, test, test. If I get enough positive feedback, I may be >> able to squeeze it into 7.1-RELEASE, but this might be hard. > > I currently don't have high-end (4 CPU+) AMD64 machines to test, but > with 1 CPU i386 virtual machine in VMWare, with 1 GB of memory, > kmem_size=kmem_size_max=512M and no other tuning, with latest zpool > format (11) it took about 15 minutes to get a "kmem_map too small" panic > on a mixed load (buildkernel + blogbench + bonnie++). > > I've then tried the same load on the "real" hardware, 2 CPU, 2 GB > memory, kmem_size=kmem_size_max=512M, and no other tuning, with the > older zpool format (6) i get the same panic, though it takes about twice > as long to happen. Have you tried tuning arc_max and/or monitoring vmstat -m to see what is happening? What does arc_max get auto-tuned to at the moment (ie. without manually specifying)? One of the things I recall reading that arc_max is more like a guide, as some ZFS threads can exceed the max whilst other thread(s) go around cleaning up and freeing memory once the limit is hit. Maybe some better smarts are needed in auto-tuning arc_max so that it leaves more of a buffer zone than it does at the moment...? --Antony
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