Date: Mon, 14 Jan 2013 20:51:48 +0100 From: Nicolas Rachinsky <fbsd-mas-0@ml.turing-complete.org> To: Artem Belevich <art@freebsd.org> Cc: freebsd-fs <freebsd-fs@freebsd.org> Subject: Re: slowdown of zfs (tx->tx) Message-ID: <20130114195148.GA20540@mid.pc5.i.0x5.de> In-Reply-To: <CAFqOu6hxfGt_M6Jo9qWeifDz9YnNc_Bd9H-GEe4RYtutaPvH5w@mail.gmail.com> References: <20130108174225.GA17260@mid.pc5.i.0x5.de> <CAFqOu6jgA8RWV5d%2BrOBk8D=3Vu3yWSnDkAi1cFJ0esj4OpBy2Q@mail.gmail.com> <20130109162613.GA34276@mid.pc5.i.0x5.de> <CAFqOu6jrng=v8eVyhqV-PBqJM_dYy%2BU7X4%2B=ahBeoxvK4mxcSA@mail.gmail.com> <20130110193949.GA10023@mid.pc5.i.0x5.de> <20130111073417.GA95100@mid.pc5.i.0x5.de> <CAFqOu6gWpMsWN0pTBiv10WfwyGWMfO9GzMLWTtcVxHixr-_i3Q@mail.gmail.com> <20130114094010.GA75529@mid.pc5.i.0x5.de> <CAFqOu6hxfGt_M6Jo9qWeifDz9YnNc_Bd9H-GEe4RYtutaPvH5w@mail.gmail.com>
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* Artem Belevich <art@freebsd.org> [2013-01-14 11:13 -0800]: > On Mon, Jan 14, 2013 at 1:40 AM, Nicolas Rachinsky > <fbsd-mas-0@ml.turing-complete.org> wrote: > > 5 Reallocated_Sector_Ct 0x0033 094 094 010 Pre-fail Always - 166 > > 195 Hardware_ECC_Recovered 0x001a 100 100 000 Old_age Always - 1259614646 > > 196 Reallocated_Event_Count 0x0032 096 096 000 Old_age Always - 166 > > > Reallocated_Sector_Ct did not increase during the last days. > > It does not matter IMHO. That hard drive already got quite a few bad > sectors that ECC could not deal with. There are apparently more > marginally bad sectors, but ECC deals with it for now. Once enough > bits rot, you'll get more bad sectors. I personally would replace the > drive. Yes, I'll do that. > >> Cound you do gstat with 1-second interval. Some of the 5-second > >> samples show that ada8 is the bottleneck -- it has its request queue > >> full (L(q)=10) when all other drives were done with their jobs. And > >> that's a 5-sec average. Its write service time also seems to be a lot > >> higher than for other drives. > > > > Attached. I have replace ada8 by ada9, which is a Western Digital > > Caviar Black. > > > > Now ada0 and ada4 seem to be the bottleneck. > > > > But I don't understand the intervalls without any disk activity. > > It is puzzling. Is rsync still sleeping in tx->tx state? Try running > "procstat -kk <rsync-PID>" periodically. It will print in-kernel stack > trace and may help giving a clue where/why rsync is stuck. # sh -c 'for i in `jot 100`; do procstat -kk 36639 ; sleep 1; done' | sort | uniq -c 100 PID TID COMM TDNAME KSTACK 1 36639 100574 rsync - <running> 99 36639 100574 rsync - mi_switch+0x176 sleepq_wait+0x42 _cv_wait+0x129 txg_wait_open+0x85 zfs_freebsd_write+0x3a6 VOP_WRITE_APV+0xb2 vn_write+0x373 dofilewrite+0x8b kern_writev+0x60 write+0x55 amd64_syscall+0x1f4 Xfast_syscall+0xfc # sh -c 'for i in `jot 100`; do procstat -kk 36639 ; sleep 0.36; done' | sort | uniq -c 100 PID TID COMM TDNAME KSTACK 1 36639 100574 rsync - mi_switch+0x176 sleepq_timedwait+0x42 _cv_timedwait+0x134 txg_delay+0x137 dsl_pool_tempreserve_space+0xd5 dsl_dir_tempreserve_space+0x154 dmu_tx_assign+0x370 zfs_freebsd_write+0x38a VOP_WRITE_APV+0xb2 vn_write+0x373 dofilewrite+0x8b kern_writev+0x60 write+0x55 amd64_syscall+0x1f4 Xfast_syscall+0xfc 99 36639 100574 rsync - mi_switch+0x176 sleepq_wait+0x42 _cv_wait+0x129 txg_wait_open+0x85 zfs_freebsd_write+0x3a6 VOP_WRITE_APV+0xb2 vn_write+0x373 dofilewrite+0x8b kern_writev+0x60 write+0x55 amd64_syscall+0x1f4 Xfast_syscall+0xfc # sh -c 'for i in `jot 100`; do procstat -kk 36639 ; sleep 0.1; done' | sort | uniq -c 100 PID TID COMM TDNAME KSTACK 100 36639 100574 rsync - mi_switch+0x176 sleepq_wait+0x42 _cv_wait+0x129 txg_wait_open+0x85 zfs_freebsd_write+0x3a6 VOP_WRITE_APV+0xb2 vn_write+0x373 dofilewrite+0x8b kern_writev+0x60 write+0x55 amd64_syscall+0x1f4 Xfast_syscall+0xfc Thanks in advance Nicolas -- http://www.rachinsky.de/nicolas
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