Date: Fri, 7 Sep 2018 10:27:49 -0700 From: Cy Schubert <Cy.Schubert@cschubert.com> To: Mark Johnston <markj@freebsd.org>, Jakob Alvermark <jakob@alvermark.net> Cc: Subbsd <subbsd@gmail.com>, "allanjude@freebsd.org" <allanjude@freebsd.org>, freebsd-current Current <freebsd-current@freebsd.org> Subject: RE: ZFS perfomance regression in FreeBSD 12 APLHA3->ALPHA4 Message-ID: <20180907172843.38609A00@spqr.komquats.com>
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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@cschubert.com> or <cy@freebsd.org> The need of the many outweighs the greed of the few. --- -----Original Message----- From: Mark Johnston Sent: 07/09/2018 09:09 To: Jakob Alvermark Cc: Subbsd; allanjude@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@freebsd.org> wrot= e: > >>> 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=3D"128M" > >>>> > >>>> I know that this is very small. However, for two years with this the= re > >>>> 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 0.00= s 0% 2676k > >>>> load: 0.34 cmd: find 5993 [arc_reclaim_waiters_cv] 1.25r 0.00u 0.00= s 0% 2680k > >>>> load: 0.34 cmd: find 5993 [arc_reclaim_waiters_cv] 1.38r 0.00u 0.00= s 0% 2684k > >>>> load: 0.34 cmd: find 5993 [arc_reclaim_waiters_cv] 1.51r 0.00u 0.00= s 0% 2704k > >>>> load: 0.34 cmd: find 5993 [arc_reclaim_waiters_cv] 1.64r 0.00u 0.00= s 0% 2716k > >>>> load: 0.34 cmd: find 5993 [arc_reclaim_waiters_cv] 1.78r 0.00u 0.00= s 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@freebs= d.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=3D338416&r2=3D338415&pathrev=3D338416 > >> ). 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+ >=20 > Hi, >=20 > I am experiencing the same slowness when there is a bit of load on the=20 > 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=3D2G. >=20 > Top is reporting >=20 > ARC: 607M Total, 140M MFU, 245M MRU, 1060K Anon, 4592K Header, 217M Other > =A0=A0=A0=A0 105M Compressed, 281M Uncompressed, 2.67:1 Ratio >=20 > Should I test the patch? I would be interested in the results, assuming it is indeed a regression. _______________________________________________ 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"
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