Date: Tue, 15 Jan 2008 02:03:16 +0000 From: Thomas Hurst <tom.hurst@clara.net> To: John Baldwin <jhb@freebsd.org> Cc: Peter Jeremy <peterjeremy@optushome.com.au>, Kris Kennaway <kris@freebsd.org>, freebsd-stable@freebsd.org Subject: Re: Swapping caused by very large (regular) file size Message-ID: <20080115020316.GA47831@voi.aagh.net> In-Reply-To: <200801120005.38972.jhb@freebsd.org> References: <20071203054207.GA1153@aleph.niw.com.au> <4787AAF4.1020905@FreeBSD.org> <20080112033147.GX60060@server.vk2pj.dyndns.org> <200801120005.38972.jhb@freebsd.org>
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* John Baldwin (jhb@freebsd.org) wrote:
> We have noticed an issue at work but only on faster controllers (e.g.
> certain mfi(4) drive configurations) when doing I/O to a single file
> like the dd command mentioned causes the buffer cache to fill up. The
> problem being that we can't lock the vm object to recycle pages when
> we hit the limit that is supposed to prevent this because all the
> pages in the cache are for the file (vm object) we are working on.
> Stephan (ups@) says this is fixed in 7.
Excellent. I've been seeing this behavior for a long time, mostly on
backup runs (RAID-1 amr SATA -> 1 disk Marvell ata). It's pretty odd
seeing a system with 8G of memory, 60% of which is just cache, swap out
half a dozen things for no apparant reason. And to think, people on
FreeNode ##freebsd just insisted I had a misconfigured system ;)
My other IO related issue with 6 is IO to independent amr arrays
blocking each other; e.g. daily run's find over amrd0 will invariably
cause reads from amrd1 and amrd2 to freeze for seconds at a time (pr
114438). I'll be very interested to see if 7 fixes that.
--
Thomas 'Freaky' Hurst
http://hur.st/
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