Date: Fri, 7 Sep 2018 12:06:54 -0400 From: Mark Johnston <markj@freebsd.org> To: Jakob Alvermark <jakob@alvermark.net> Cc: Subbsd <subbsd@gmail.com>, allanjude@freebsd.org, freebsd-current Current <freebsd-current@freebsd.org> Subject: Re: ZFS perfomance regression in FreeBSD 12 APLHA3->ALPHA4 Message-ID: <20180907160654.GD63224@raichu> In-Reply-To: <26c0f87e-2dd5-b088-8edb-0790b6b01ef0@alvermark.net> References: <CAFt_eMrhFiV0OJQ2w05-pFj4EkYr9dbYf4APLuJdBykwkOjRsQ@mail.gmail.com> <e26c530e-88e4-0481-9012-f814dd8ed569@freebsd.org> <CAFt_eMozS6_9VWBu%2B3LZ9n12bFdykZkz9HTi-zb0kgSKS2Riag@mail.gmail.com> <20180906002825.GB77324@raichu> <26c0f87e-2dd5-b088-8edb-0790b6b01ef0@alvermark.net>
next in thread | previous in thread | raw e-mail | index | archive | help
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@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@freebsd.org mailing list > >>>> https://lists.freebsd.org/mailman/listinfo/freebsd-current > >>>> To unsubscribe, send any mail to "freebsd-current-unsubscribe@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.
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20180907160654.GD63224>