Total MFU MRU Anon Hdr L2Hdr Other ZFS ARC 667M 186M 168M 13M 3825K 0K 295M rate hits misses total hits total misses arcstats : 99% 65636 605 167338494 9317074 arcstats.demand_data : 57% 431 321 13414675 2117714 arcstats.demand_metadata : 99% 65175 193 152969480 5344919 arcstats.prefetch_data : 0% 0 30 3292 401344 arcstats.prefetch_metadata: 32% 30 61 951047 1453097 zfetchstats : 9% 119 1077 612582 55041789 arcstats.l2 : 0% 0 0 0 0 vdev_cache_stats : 0% 0 0 0 0 This is while a 'make -j8 buildworld' (it has 8 cores) is going. SSH'ing to the machine while the buildworld is going it takes 40-60 seconds to get to the shell! Hitting ^T while waiting: load: 1.06 cmd: zsh 45334 [arc_reclaim_waiters_cv] 56.11r 0.00u 0.10s 0% 5232k I will test the patch below and report back. Jakob On 9/7/18 7:27 PM, Cy Schubert wrote: > I'd be interested in seeing systat -z output. > > --- > Sent using a tiny phone keyboard. > Apologies for any typos and autocorrect. > Also, this old phone only supports top post. Apologies. > > Cy Schubert > <Cy.Schubert_at_cschubert.com> or <cy_at_freebsd.org> > The need of the many outweighs the greed of the few. > --- > ------------------------------------------------------------------------ > From: Mark Johnston > Sent: 07/09/2018 09:09 > To: Jakob Alvermark > Cc: Subbsd; allanjude_at_freebsd.org; freebsd-current Current > Subject: Re: ZFS perfomance regression in FreeBSD 12 APLHA3->ALPHA4 > > On Fri, Sep 07, 2018 at 03:40:52PM +0200, Jakob Alvermark wrote: > > On 9/6/18 2:28 AM, Mark Johnston wrote: > > > On Wed, Sep 05, 2018 at 11:15:03PM +0300, Subbsd wrote: > > >> On Wed, Sep 5, 2018 at 5:58 PM Allan Jude <allanjude_at_freebsd.org> > wrote: > > >>> On 2018-09-05 10:04, Subbsd wrote: > > >>>> Hi, > > >>>> > > >>>> I'm seeing a huge loss in performance ZFS after upgrading > FreeBSD 12 > > >>>> to latest revision (r338466 the moment) and related to ARC. > > >>>> > > >>>> I can not say which revision was before except that the newver.sh > > >>>> pointed to ALPHA3. > > >>>> > > >>>> Problems are observed if you try to limit ARC. In my case: > > >>>> > > >>>> vfs.zfs.arc_max="128M" > > >>>> > > >>>> I know that this is very small. However, for two years with > this there > > >>>> were no problems. > > >>>> > > >>>> When i send SIGINFO to process which is currently working with > ZFS, i > > >>>> see "arc_reclaim_waiters_cv": > > >>>> > > >>>> e.g when i type: > > >>>> > > >>>> /bin/csh > > >>>> > > >>>> I have time (~5 seconds) to press several times 'ctrl+t' before > csh is executed: > > >>>> > > >>>> load: 0.70 cmd: csh 5935 [arc_reclaim_waiters_cv] 1.41r 0.00u > 0.00s 0% 3512k > > >>>> load: 0.70 cmd: csh 5935 [zio->io_cv] 1.69r 0.00u 0.00s 0% 3512k > > >>>> load: 0.70 cmd: csh 5935 [arc_reclaim_waiters_cv] 1.98r 0.00u > 0.01s 0% 3512k > > >>>> load: 0.73 cmd: csh 5935 [arc_reclaim_waiters_cv] 2.19r 0.00u > 0.01s 0% 4156k > > >>>> > > >>>> same story with find or any other commans: > > >>>> > > >>>> load: 0.34 cmd: find 5993 [zio->io_cv] 0.99r 0.00u 0.00s 0% 2676k > > >>>> load: 0.34 cmd: find 5993 [arc_reclaim_waiters_cv] 1.13r 0.00u > 0.00s 0% 2676k > > >>>> load: 0.34 cmd: find 5993 [arc_reclaim_waiters_cv] 1.25r 0.00u > 0.00s 0% 2680k > > >>>> load: 0.34 cmd: find 5993 [arc_reclaim_waiters_cv] 1.38r 0.00u > 0.00s 0% 2684k > > >>>> load: 0.34 cmd: find 5993 [arc_reclaim_waiters_cv] 1.51r 0.00u > 0.00s 0% 2704k > > >>>> load: 0.34 cmd: find 5993 [arc_reclaim_waiters_cv] 1.64r 0.00u > 0.00s 0% 2716k > > >>>> load: 0.34 cmd: find 5993 [arc_reclaim_waiters_cv] 1.78r 0.00u > 0.00s 0% 2760k > > >>>> > > >>>> this problem goes away after increasing vfs.zfs.arc_max > > >>>> _______________________________________________ > > >>>> freebsd-current_at_freebsd.org mailing list > > >>>> https://lists.freebsd.org/mailman/listinfo/freebsd-current > > >>>> To unsubscribe, send any mail to > "freebsd-current-unsubscribe_at_freebsd.org" > > >>>> > > >>> Previously, ZFS was not actually able to evict enough dnodes to keep > > >>> your arc_max under 128MB, it would have been much higher based > on the > > >>> number of open files you had. A recent improvement from upstream ZFS > > >>> (r337653 and r337660) was pulled in that fixed this, so setting an > > >>> arc_max of 128MB is much more effective now, and that is causing the > > >>> side effect of "actually doing what you asked it to do", in this > case, > > >>> what you are asking is a bit silly. If you have a working set > that is > > >>> greater than 128MB, and you ask ZFS to use less than that, it'll > have to > > >>> constantly try to reclaim memory to keep under that very low bar. > > >>> > > >> Thanks for comments. Mark was right when he pointed to r338416 ( > > >> > https://svnweb.freebsd.org/base/head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c?r1=338416&r2=338415&pathrev=338416 > > >> ). Commenting aggsum_value returns normal speed regardless of the > rest > > >> of the new code from upstream. > > >> I would like to repeat that the speed with these two lines is not > just > > >> slow, but _INCREDIBLY_ slow! Probably, this should be written in the > > >> relevant documentation for FreeBSD 12+ > > > > Hi, > > > > I am experiencing the same slowness when there is a bit of load on the > > system (buildworld for example) which I haven't seen before. > > Is it a regression following a recent kernel update? > > > I have vfs.zfs.arc_max=2G. > > > > Top is reporting > > > > ARC: 607M Total, 140M MFU, 245M MRU, 1060K Anon, 4592K Header, 217M > Other > > 105M Compressed, 281M Uncompressed, 2.67:1 Ratio > > > > Should I test the patch? > > I would be interested in the results, assuming it is indeed a > regression. > _______________________________________________ > freebsd-current_at_freebsd.org mailing list > https://lists.freebsd.org/mailman/listinfo/freebsd-current > To unsubscribe, send any mail to "freebsd-current-unsubscribe_at_freebsd.org" >Received on Sat Sep 08 2018 - 08:40:10 UTC
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