Date: Tue, 15 Jan 2008 10:21:08 +0100 From: Kris Kennaway <kris@FreeBSD.org> To: John Baldwin <jhb@freebsd.org>, freebsd-stable@freebsd.org, Peter Jeremy <peterjeremy@optushome.com.au>, Kris Kennaway <kris@freebsd.org> Subject: Re: Swapping caused by very large (regular) file size Message-ID: <478C7B04.9080102@FreeBSD.org> In-Reply-To: <20080115020316.GA47831@voi.aagh.net> References: <20071203054207.GA1153@aleph.niw.com.au> <4787AAF4.1020905@FreeBSD.org> <20080112033147.GX60060@server.vk2pj.dyndns.org> <200801120005.38972.jhb@freebsd.org> <20080115020316.GA47831@voi.aagh.net>
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Thomas Hurst wrote: > * 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. Sounds like it might be due to Giant contention, which I think is indeed fixed in 7. Can you try it? Kris
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