Date: Wed, 7 Apr 2010 23:25:57 -0400 From: Rich <rincebrain@gmail.com> To: Adam Nowacki <nowak@xpam.de> Cc: freebsd-fs@freebsd.org Subject: Re: ZFS arc sizing (maybe related to kern/145229) Message-ID: <i2l5da0588e1004072025w953351c1l8400fbd0c1766c5f@mail.gmail.com> In-Reply-To: <4BBD15E7.5010006@xpam.de> References: <z2o5a1151761004071105kb129ca4q7dfd002270d53561@mail.gmail.com> <h2u5da0588e1004071146lf09ef89eo217933f75ec7a88b@mail.gmail.com> <4BBD15E7.5010006@xpam.de>
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kstat.zfs.misc.arcstats.memory_throttle_count: 673016 Since UFS has no files of any reasonable size on it (it's literally just rootFS)... - Rich On Wed, Apr 7, 2010 at 7:31 PM, Adam Nowacki <nowak@xpam.de> wrote: > check kstat.zfs.misc.arcstats.memory_throttle_count > This counter is increased every time zfs thinks system is running low on > memory and will force a write flush and reduce arc size to minimum. Bigge= st > problem is that the code is counting only free memory and completely > ignoring other memory that can be immediately freed like cached files fro= m > ufs. This is very easy to trigger on mixed ufs and zfs system by just > reading enough data from ufs to fill its cache, zfs will begin throttling > and will continue doing so even with no further ufs reads or writes. > > Rich wrote: >> >> A datapoint for you: >> Now running 8-STABLE (plus the mbuf leak fix which went in recently), >> here's my ARC stats and ARC sysctl settings after the server was up >> for about a week (5 days) after that: >> ARC Size: >> =A0 =A0 =A0 =A0Current Size: =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0= =A0 =A0 587.49M (arcsize) >> =A0 =A0 =A0 =A0Target Size: (Adaptive) =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 5= 87.63M (c) >> =A0 =A0 =A0 =A0Min Size (Hard Limit): =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 = =A0512.00M (arc_min) >> =A0 =A0 =A0 =A0Max Size (Hard Limit): =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 = =A03072.00M (arc_max) >> >> ARC Size Breakdown: >> =A0 =A0 =A0 =A0Recently Used Cache Size: =A0 =A0 =A0 98.28% =A0577.50M (= p) >> =A0 =A0 =A0 =A0Frequently Used Cache Size: =A0 =A0 1.72% =A0 10.12M (c-p= ) >> >> ARC Efficiency: >> =A0 =A0 =A0 =A0Cache Access Total: =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 = =A0 2602789964 >> =A0 =A0 =A0 =A0Cache Hit Ratio: =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A096.11% = =A02501461882 >> =A0 =A0 =A0 =A0Cache Miss Ratio: =A0 =A0 =A0 =A0 =A0 =A0 =A0 3.89% =A0 1= 01328082 >> =A0 =A0 =A0 =A0Actual Hit Ratio: =A0 =A0 =A0 =A0 =A0 =A0 =A0 87.65% =A02= 281380527 >> >> and >> >> =A0 =A0 =A0 =A0vfs.zfs.arc_meta_limit=3D1073741824 >> =A0 =A0 =A0 =A0vfs.zfs.arc_meta_used=3D548265792 >> =A0 =A0 =A0 =A0vfs.zfs.arc_min=3D536870912 >> =A0 =A0 =A0 =A0vfs.zfs.arc_max=3D3221225472 >> >> So it very clearly limits to near the minimum size, but whether this >> is design or accidental behavior, I'm unsure. >> _______________________________________________ >> freebsd-fs@freebsd.org mailing list >> http://lists.freebsd.org/mailman/listinfo/freebsd-fs >> To unsubscribe, send any mail to "freebsd-fs-unsubscribe@freebsd.org" >> >> > > _______________________________________________ > freebsd-fs@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-fs > To unsubscribe, send any mail to "freebsd-fs-unsubscribe@freebsd.org" >
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