Date: Wed, 8 Feb 2012 16:43:48 -0800 From: Artem Belevich <art@freebsd.org> To: Jeremy Chadwick <freebsd@jdc.parodius.com> Cc: "Eugene M. Zheganin" <emz@norma.perm.ru>, freebsd-stable <freebsd-stable@freebsd.org>, Miroslav Lachman <000.fbsd@quip.cz>, Andriy Gapon <avg@freebsd.org>, mm@freebsd.org Subject: Re: zfs arc and amount of wired memory Message-ID: <CAFqOu6jdHXs02918q28RUo_KSyhW2OdHkLyerM4fZVstR1MCEA@mail.gmail.com> In-Reply-To: <20120209002835.GA29400@icarus.home.lan> References: <4F310115.3070507@FreeBSD.org> <4F310C5A.6070400@norma.perm.ru> <4F310E75.7090301@FreeBSD.org> <4F3144A9.2000505@norma.perm.ru> <4F314892.50806@FreeBSD.org> <4F314B5B.100@norma.perm.ru> <4F3186C6.8000904@FreeBSD.org> <4F324F10.2060508@norma.perm.ru> <4F32DB30.6020600@FreeBSD.org> <4F330F38.3010806@quip.cz> <20120209002835.GA29400@icarus.home.lan>
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On Wed, Feb 8, 2012 at 4:28 PM, Jeremy Chadwick <freebsd@jdc.parodius.com> wrote: > On Thu, Feb 09, 2012 at 01:11:36AM +0100, Miroslav Lachman wrote: ... >> ARC Size: >> =A0 =A0 =A0 =A0 =A0Current Size: =A0 =A0 =A0 =A0 =A0 =A0 1769 MB (arcsiz= e) >> =A0 =A0 =A0 =A0 =A0Target Size (Adaptive): =A0 512 MB (c) >> =A0 =A0 =A0 =A0 =A0Min Size (Hard Limit): =A0 =A0512 MB (zfs_arc_min) >> =A0 =A0 =A0 =A0 =A0Max Size (Hard Limit): =A0 =A03584 MB (zfs_arc_max) >> >> The target size is going down to the min size and after few more >> days, the system is so slow, that I must reboot the machine. Then it >> is running fine for about 107 days and then it all repeat again. >> >> You can see more on MRTG graphs >> http://freebsd.quip.cz/ext/2012/2012-02-08-kiwi-mrtg-12-15/ >> You can see links to other useful informations on top of the page >> (arc_summary, top, dmesg, fs usage, loader.conf) >> >> There you can see nightly backups (higher CPU load started at >> 01:13), otherwise the machine is idle. >> >> It coresponds with ARC target size lowering in last 5 days >> http://freebsd.quip.cz/ext/2012/2012-02-08-kiwi-mrtg-12-15/local_zfs_arc= stats_size.html >> >> And with ARC metadata cache overflowing the limit in last 5 days >> http://freebsd.quip.cz/ext/2012/2012-02-08-kiwi-mrtg-12-15/local_zfs_vfs= _meta.html >> >> I don't know what's going on and I don't know if it is something >> know / fixed in newer releases. We are running a few more ZFS >> systems on 8.2 without this issue. But those systems are in >> different roles. > > This sounds like the... damn, what is it called... some kind of internal > "counter" or "ticks" thing within the ZFS code that was discovered to > only begin happening after a certain period of time (which correlated to > some number of days, possibly 107). =A0I'm sorry that I can't be more > specific, but it's been discussed heavily on the lists in the past, and > fixes for all of that were committed to RELENG_8. =A0I wish I could > remember the name of the function or macro or variable name it pertained > to, something like LTHAW or TLOCK or something like that. =A0I would say > "I don't know why I can't remember", but I do know why I can't remember: > because I gave up trying to track all of these problems. > > Does someone else remember this issue? =A0CC'ing Martin who might remembe= r > for certain. It's LBOLT. :-) And there was more than one related integer overflow. One of them manifested itself as L2ARC feeding thread hogging CPU time after about a month of uptime. Another one caused issue with ARC reclaim after 107 days. See more details in this thread: http://lists.freebsd.org/pipermail/freebsd-fs/2011-May/011584.html --Artem
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