Date: Fri, 31 Dec 2010 10:39:09 -0700 From: David Samms <dsamms@nw-ds.com> To: freebsd-fs@freebsd.org Subject: Re: 8.2-RC1 and ZFS Message-ID: <ifl4fu$uei$1@dough.gmane.org> In-Reply-To: <8639pe55zj.fsf@gmail.com> References: <4D1BCE34.4090601@nw-ds.com> <20101230085723.GA38391@tolstoy.tols.org> <ifidg5$qeq$1@dough.gmane.org> <ifjgsu$s33$1@dough.gmane.org> <8639pe55zj.fsf@gmail.com>
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On 12/31/10 08:14, Anonymous wrote: > David Samms<dsamms@nw-ds.com> writes: > > [...] >> The same test with ZFSv28 and ZFSv28 + tuning >> >> ZFSv28 >> ---------------------------------------------------------------------- >> dd if=/dev/zero of=big bs=1m count=6400 >> 6710886400 bytes transferred in 158.205268 secs (42418855 bytes/sec) >> >> OpenOffice 197sec >> MP3 skips >> XFCE4 popup menus took 5-15 seconds to appear >> >> >> ZFSv28 + tuning >> --vfs.zfs.txg.timeout="5" > > the tunable defaults to "5" in v28, see txg.c > > int zfs_txg_timeout = 5; /* max seconds worth of delta per txg */ > >> --vfs.zfs.txg.write_limit_override=268435456 > > No such tunable/sysctl. It was renamed to vfs.zfs.write_limit_override > in v28 (note ".txg." absence). > >> --kern.maxvnodes=250000 > >> ---------------------------------------------------------------------- >> dd if=/dev/zero of=big bs=1m count=6400 >> 6710886400 bytes transferred in 167.316444 secs (40108947 bytes/sec) >> >> OpenOffice 190sec >> No MP3 skips during "dd", but one skip while OpenOffice was starting >> XFCE4 popup menus took 2-13 seconds to appear Thank you for the correction. Please disregard my previous test results for ZFS+tuning. Below are the corrected results: ZFSv28 defaults + -- vfs.zfs.write_limit_override: 268435456 -- kern.maxvnodes=250000 ---------------------------------------------------------------------- dd if=/dev/zero of=big bs=1m count=6400 6710886400 bytes transferred in 254.771374 secs (26340818 bytes/sec) OpenOffice 82sec No Skips menus 0-1 sec ZFSv28 defaults + -- vfs.zfs.write_limit_override: 1073741824 -- kern.maxvnodes=250000 ---------------------------------------------------------------------- dd if=/dev/zero of=big bs=1m count=6400 6710886400 bytes transferred in 189.671025 secs (35381716 bytes/sec) OpenOffice 190sec No Skips menus 0-2 sec Setting vfs.zfs.write_limit_override: 268435456 significantly slows writes but make reads wonderful. Not ideal though. Setting vfs.zfs.write_limit_override: 1073741824 brings writes up to 87% of UFS+s and _dramatically_ improves GUI responsiveness. Very good setting for an old desktop machine. Being a ZFS novice, I would appreciate any links to tuning information. The default ZFS tuning do not seem good for a web-server or desktop which is fine, but guiding sysadmins to typical settings for their application would be helpful.
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