In your case there your vdev (ada0) is saturated with writes from postgres.
You should consider more / faster disks.
You might also want to consider enabling lz4 compression on the PG
volume as its works well in IO bound situations.
On 21/10/2016 01:54, Jonathan Chen wrote:
On 21 October 2016 at 12:56, Steven Hartland <kill...@multiplay.co.uk> wrote:
[...]
When you see the stalling what does gstat -pd and top -SHz show?
On my dev box:
1:38pm# uname -a
FreeBSD irontree 10.3-STABLE FreeBSD 10.3-STABLE #0 r307401: Mon Oct
17 10:17:22 NZDT 2016 root@irontree:/usr/obj/usr/src/sys/GENERIC
amd64
1:49pm# gstat -pd
dT: 1.004s w: 1.000s
L(q) ops/s r/s kBps ms/r w/s kBps ms/w d/s kBps
ms/d %busy Name
0 0 0 0 0.0 0 0 0.0 0 0
0.0 0.0| cd0
18 618 1 128 41.4 606 52854 17.2 0 0
0.0 100.5| ada0
^C
1:49pm# top -SHz
last pid: 83284; load averages: 0.89, 0.68, 0.46
up
4+03:11:32 13:49:05
565 processes: 9 running, 517 sleeping, 17 zombie, 22 waiting
CPU: 3.7% user, 0.0% nice, 1.9% system, 0.0% interrupt, 94.3% idle
Mem: 543M Active, 2153M Inact, 11G Wired, 10M Cache, 2132M Free
ARC: 7249M Total, 1325M MFU, 4534M MRU, 906M Anon, 223M Header, 261M Other
Swap: 32G Total, 201M Used, 32G Free
PID USERNAME PRI NICE SIZE RES STATE C TIME WCPU COMMAND
83149 postgres 38 0 2197M 528M zio->i 5 1:13 23.19% postgres
83148 jonc 22 0 36028K 13476K select 2 0:11 3.86% pg_restore
852 postgres 20 0 2181M 2051M select 5 0:27 0.68% postgres
0 root -15 - 0K 4240K - 6 0:50 0.49%
kernel{zio_write_issue_}
0 root -15 - 0K 4240K - 6 0:50 0.39%
kernel{zio_write_issue_}
0 root -15 - 0K 4240K - 6 0:50 0.39%
kernel{zio_write_issue_}
0 root -15 - 0K 4240K - 7 0:50 0.39%
kernel{zio_write_issue_}
0 root -15 - 0K 4240K - 7 0:50 0.39%
kernel{zio_write_issue_}
0 root -15 - 0K 4240K - 7 0:50 0.29%
kernel{zio_write_issue_}
3 root -8 - 0K 112K zio->i 6 1:50 0.20%
zfskern{txg_thread_enter}
12 root -88 - 0K 352K WAIT 0 1:07 0.20%
intr{irq268: ahci0}
0 root -16 - 0K 4240K - 4 0:29 0.20%
kernel{zio_write_intr_4}
0 root -16 - 0K 4240K - 7 0:29 0.10%
kernel{zio_write_intr_6}
0 root -16 - 0K 4240K - 0 0:29 0.10%
kernel{zio_write_intr_1}
0 root -16 - 0K 4240K - 5 0:29 0.10%
kernel{zio_write_intr_2}
0 root -16 - 0K 4240K - 1 0:29 0.10%
kernel{zio_write_intr_5}
...
Taking another look at the internal dir structure for postgres, I'm
not too sure whether this is related to the original poster's problem
though.
Cheers.
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