Date: Wed, 20 Jan 2010 11:47:30 +0100 From: Alexander Leidinger <Alexander@Leidinger.net> To: Jeremy Chadwick <freebsd@jdc.parodius.com> Cc: freebsd-stable@FreeBSD.org Subject: Re: ZFS performance degradation over time Message-ID: <20100120114730.916917ef0eu668n4@webmail.leidinger.net> In-Reply-To: <20100119170101.GA80917@icarus.home.lan> References: <7346c5c61001030842r7dc76199y51e4c1c90a3eea6e@mail.gmail.com> <7346c5c61001091706m45a3a2a5k3ca8bb0c4bec5ea8@mail.gmail.com> <7346c5c61001171521w1ca4738w98e8fcca24643cda@mail.gmail.com> <201001180829.48126.npapke@acm.org> <7346c5c61001190840k31466754i32b2ae833390b79b@mail.gmail.com> <20100119170101.GA80917@icarus.home.lan>
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Quoting Jeremy Chadwick <freebsd@jdc.parodius.com> (from Tue, 19 Jan 2010 09:01:01 -0800): > On Tue, Jan 19, 2010 at 11:40:50AM -0500, Garrett Moore wrote: >> I've been watching my memory usage and I have no idea what is consuming >> memory as 'Active'. >> >> Last night I had around 6500MB 'Active' again, 1500MB Wired, no inact, ~30MB >> buf, no free, and ~100MB swap used. My performance copying ZFS->ZFS was >> again slow (<1MB/s). I tried killing rTorrent and no significant amount of >> memory was reclaimed - maybe 100MB. `ps aux` showed no processes using any >> significant amount of memory, and I was definitely nowhere near 6500MB >> usage. >> >> I tried running the perl oneliner again to hog a bunch of memory, and almost >> all of the Active memory was IMMEDIATELY marked as Free, and my performance >> was excellent again. >> >> I'm not sure what in userland could be causing the issue. The only things >> I've installed are rTorrent, lighttpd, samba, smartmontools, vim, bash, >> Python, Perl, and SABNZBd. There is nothing that *should* be consuming any >> serious amount of memory. > > I've two recommendations: > > 1) Have you considered "upgrading" to RELENG_8 (e.g. 8.0-STABLE) instead > of sticking with 8.0-RELEASE? There's been a recent MFC to RELENG_8 > which pertain to ARC drainage. I'm referring to the commit labelled > revision 1.22.2.2 (RELENG_8): > > http://www.freebsd.org/cgi/cvsweb.cgi/src/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c This patch can be merged stand-alone if necessary, no need to go to RELENG_8 if there are reservations. > 2) Have you tried using vfs.zfs.arc_max in loader.conf to limit the ARC > size? I'd recommend picking something like 1GB as a cap (your machine Or even less... to be determined by experimenting. > has 8GB total at present, if I remember right). I believe long ago > someone said this isn't an explicit hard limit on the maximum size of > the ARC, but I believe this was during the RELENG_7 days and the ARC > "stuff" on FreeBSD has changed since then. I wish the tunables were > better documented, or at least explained in detail (hello Wiki!). The commit you refer to above is just doing this: limiting the arc more to the arc_max than it was the case before. This patch is in 7-stable too (in case someone is interested). Bye, Alexander. -- Johnson's First Law: When any mechanical contrivance fails, it will do so at the most inconvenient possible time. http://www.Leidinger.net Alexander @ Leidinger.net: PGP ID = B0063FE7 http://www.FreeBSD.org netchild @ FreeBSD.org : PGP ID = 72077137
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