Date: Tue, 05 Apr 2011 16:51:12 +0300 From: Andriy Gapon <avg@FreeBSD.org> To: Jeremy Chadwick <freebsd@jdc.parodius.com>, Boris Kochergin <spawk@acm.poly.edu> Cc: FreeBSD-STABLE Mailing List <freebsd-stable@FreeBSD.org> Subject: Re: Kernel memory leak in 8.2-PRERELEASE? Message-ID: <4D9B1E50.9020403@FreeBSD.org> In-Reply-To: <20110405010148.GA67821@icarus.home.lan> References: <4D972FF7.6010901@acm.poly.edu> <20110402153315.GP78089@deviant.kiev.zoral.com.ua> <4D974393.80606@acm.poly.edu> <4D9A307F.9070408@acm.poly.edu> <20110404224334.GA64297@icarus.home.lan> <4D9A68AA.6040803@acm.poly.edu> <20110405010148.GA67821@icarus.home.lan>
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on 05/04/2011 04:01 Jeremy Chadwick said the following: > On Mon, Apr 04, 2011 at 08:56:10PM -0400, Boris Kochergin wrote: >> No swap, blank /boot/loader.conf, default /etc/sysctl.conf. I'm >> going to try this ARC tuning thing. I vaguely recall several claims >> that tuning wasn't necessary anymore on amd64 systems with the >> amount of memory mine has, but that's obviously not the case. > > Given that you don't have swap (again: very, very bad idea), your > applications crashing due to there not being any swap space is expected: > no place to swap them out to. Jeremy, very true indeed. Boris, ARC is an adaptive cache (as its name says), but the adaption doesn't happen instantly. So, when your applications do not use a lot of memory, but there is steady filesystem usage, then ZFS ARC is going to gradually grow to consume an optimum amount of RAM. Then, your applications suddenly need a lot more memory, they put pressure on VM system, ARC starts to shrink. But if memory demand grows faster than ARC shrinks, you are going to get a memory shortage. And since you don't have any swap to act as a safety net, you are getting out-of-memory situation. So no surprises here, no system problems, just a normal foot-shooting :) Clamping maximum ARC size, as Jeremy has suggested, should help some. Adding some swap would help a lot more. -- Andriy Gapon
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