Date: Wed, 5 Sep 2018 17:04:56 +0300 From: Subbsd <subbsd@gmail.com> To: freebsd-current Current <freebsd-current@freebsd.org>, freebsd-fs@freebsd.org Subject: ZFS perfomance regression in FreeBSD 12 APLHA3->ALPHA4 Message-ID: <CAFt_eMrhFiV0OJQ2w05-pFj4EkYr9dbYf4APLuJdBykwkOjRsQ@mail.gmail.com>
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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
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