Date: Fri, 11 Aug 2017 11:28:21 +0500 From: "Eugene M. Zheganin" <emz@norma.perm.ru> To: freebsd-fs@freebsd.org Cc: freebsd-stable <freebsd-stable@FreeBSD.org> Subject: zfs listing and CPU Message-ID: <aa26e888-05ef-c876-abf3-778ff08f4857@norma.perm.ru>
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Hi,
Why does the zfs listing eat so much of the CPU ?
last pid: 47151; load averages: 3.97, 6.35,
6.13 up 1+23:21:18 09:15:13
146 processes: 3 running, 142 sleeping, 1 waiting
CPU: 0.0% user, 0.0% nice, 30.5% system, 0.3% interrupt, 69.2% idle
Mem: 44M Active, 360M Inact, 37G Wired, 25G Free
ARC: 32G Total, 14G MFU, 17G MRU, 312M Anon, 803M Header, 523M Other
Swap: 32G Total, 185M Used, 32G Free
PID USERNAME THR PRI NICE SIZE RES STATE C TIME WCPU COMMAND
11 root 32 155 ki31 0K 512K CPU0 0 1104.1 2666.23%
idle
0 root 9880 -16 - 0K 154M swapin 11 314.0H 281.29%
kernel
13 root 3 -8 - 0K 48K gread 0 20.9H 28.71% geom
47114 root 1 20 0 40432K 3840K db->db 4 0:05 26.84% zfs
47099 root 1 20 0 40432K 3840K zio->i 17 0:05 26.83% zfs
47106 root 1 20 0 40432K 3840K db->db 21 0:05 26.81% zfs
47150 root 1 20 0 40432K 3428K db->db 13 0:03 26.31% zfs
47141 root 1 20 0 40432K 3428K zio->i 28 0:03 26.31% zfs
47135 root 1 20 0 40432K 3312K g_wait 9 0:03 25.51% zfs
4 root 7 -16 - 0K 112K - 20 975:01 19.73% cam
5 root 2494 -8 - 0K 39952K arc_re 18 20.2H 18.58%
zfskern
12 root 65 -60 - 0K 1040K WAIT 0 17.8H 15.64% intr
22 root 2 -16 - 0K 32K psleep 3 66:34 7.31%
pagedaemon
590 root 10 -16 - 0K 160K - 21 177:02 2.96% ctl
[...]
This is from winter 2017 11-STABLE (r310734), one of the 'zfs'es is
cloning, and all the others are 'zfs list -t all'. I have like 25 gigs
of free RAM, do I have any chance of speeding this up using may be some
caching or some sysctl tuning ? We are using a simple ZFS web API that
may issue concurrent or sequential listing requests, so as you can see
they sometimes do stack.
Thanks.
Eugene.
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