Date: Wed, 29 Jul 2015 14:11:59 -0700 From: javocado <javocado@gmail.com> To: FreeBSD Filesystems <freebsd-fs@freebsd.org> Subject: pw operations slow under zfs load Message-ID: <CAP1HOmTuxi7HL0_-SLJ8pd9s=3ob2D_ZU0pu%2BMSZfuxMPDydWw@mail.gmail.com>
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Hi,
We have a pretty busy ZFS pool running on an 8.3 AMD system. We are
noticing that when the pool is busy pw-related operations seem to take a
long time to complete:
# time pw unlock 1000
0.007u 0.036s 0:39.72 0.0% 45+1953k 0+113io 0pf+0w
# time pw lock 1000
0.032u 0.022s 1:09.63 0.0% 24+1132k 0+114io 0pf+0w
Wile the command is running, we note that the process is locked in the D
state:
root 85051 0.0 0.0 5832 960 0 D+ 1:53PM 0:00.02
/usr/sbin/pwd_mkdb -u 1000 /etc/master.passwd
We also note that there is next to 0 disk activity on the boot volume:
# gstat -f ad
dT: 1.005s w: 1.000s filter: ad
L(q) ops/s r/s kBps ms/r w/s kBps ms/w %busy Name
0 0 0 0 0.0 0 0 0.0 0.0| ad6
0 0 0 0 0.0 0 0 0.0 0.0| ad8
0 0 0 0 0.0 0 0 0.0 0.0| ad10
0 0 0 0 0.0 0 0 0.0 0.0| ad12
And plenty of free mem:
Mem: 400M Active, 3391M Inact, 128G Wired, 1935M Cache, 14G Buf, 6055M Free
So, what's going on here? How does a busy pool with it's own set of drives
(which operate off an HBA) affect the speed of operations involving the
boot volume (an SSD connected to the mobo)?
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