Date: Mon, 12 Oct 2009 10:32:24 +0200 From: Attila Nagy <bra@fsn.hu> To: "K. Macy" <kmacy@freebsd.org> Cc: freebsd-fs@FreeBSD.org, Pawel Jakub Dawidek <pjd@FreeBSD.org> Subject: Re: ARC size constantly shrinks, then ZFS slows down extremely Message-ID: <4AD2E998.8090409@fsn.hu> In-Reply-To: <47C0A3F4-6431-49E5-B780-FA162946C288@freebsd.org> References: <4AC1E540.9070001@fsn.hu> <4AC5B2C7.2000200@fsn.hu> <20091002184526.GA1660@garage.freebsd.pl> <4ACDA5EA.2010600@fsn.hu> <4ACDDED0.2070707@fsn.hu> <20091008160718.GB2134@garage.freebsd.pl> <4AD2E118.2050202@fsn.hu> <47C0A3F4-6431-49E5-B780-FA162946C288@freebsd.org>
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K. Macy wrote: >> >> The amd64 machine started to loose ARC memory again. See these: >> http://people.fsn.hu/~bra/freebsd/20091012-zfs-arcsize/zfs_mem-week.png >> http://people.fsn.hu/~bra/freebsd/20091012-zfs-arcsize/memory-week.png >> >> Your patch was active between 7 and 9. You can see that the ARC size >> was somewhat constant. >> On october 9, I installed Kip's modification, and ARC size started to >> decrease. >> BTW, previously (before october 7) I set the arc min size to 10-15GB >> (can't remember the exact value), but now it runs with the defaults >> (only the max size is set): >> vfs.zfs.arc_min: 3623878656 >> vfs.zfs.arc_max: 28991029248 >> >> As you can see, there are plenty of memory. This machine uses UFS as >> well (and writes it heavily), maybe that's what affects ZFS size, by >> caching a lot of stuff? >> > > Currently, the inactive page queue will grow until ARC is shrunk to > arc_min. > > > I think I'll probably spend some time making the ARC play better with > the page cache this week. Unfortunately, under heavy memory pressure > when competing with UFS the ARC will degrade to LRU, but I think that > is still an improvement over the current static sizing with low and > high water marks. Will setting ARC's minimum size help here? (I will try) For me, it's OK, and I think it's generally not a problem, if somebody uses UFS as well. Is it possible to merge the memory management of the two, or they are completely different beasts? Thanks,
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