Ivan Voras wrote:
2009/11/6 Miroslav Lachman<[email protected]>:
I do not understand why there are 10MB/s read from disks when network
traffic dropped to around 1MB/s (8Mbps)
r...@cage ~/# iostat -w 20
tty ad4 ad6 cpu
tin tout KB/t tps MB/s KB/t tps MB/s us ni sy in id
0 14 41.66 53 2.17 41.82 53 2.18 0 0 2 0 97
0 18 50.92 96 4.77 54.82 114 6.12 0 0 3 1 96
0 6 53.52 101 5.29 54.98 108 5.81 1 0 4 1 94
0 6 54.82 98 5.26 55.89 108 5.89 0 0 3 1 96
Yes, this could limit your IO if the requests are random enough.
Unfortunately I don't know how would you track down what is really
going on. Maybe some tracing with DTrace?
I'd tell you to use "top -m io" to see if there is a process
responsible, but apparently these statistics are not updated for ZFS,
which in itself may be a bug (which is why I'm crossposting to
freebsd-fs).
DTrace is totally out of my skills ;(
There is otput of top -m io sorted by VCSW displaying JID.
last pid: 17724; load averages: 0.01, 0.07, 0.08 up 74+20:49:49
21:03:40
195 processes: 1 running, 193 sleeping, 1 zombie
CPU: 0.0% user, 0.0% nice, 3.6% system, 0.4% interrupt, 96.1% idle
Mem: 462M Active, 2385M Inact, 977M Wired, 21M Cache, 399M Buf, 100M Free
Swap: 6144M Total, 2024K Used, 6142M Free
PID JID USERNAME VCSW IVCSW READ WRITE FAULT TOTAL PERCENT
COMMAND
17681 8 www 657 64 0 0 0 0 0.00%
lighttpd
17683 8 www 379 41 0 0 0 0 0.00%
lighttpd
17680 8 www 136 5 0 0 0 0 0.00%
lighttpd
17682 8 www 85 0 0 0 0 0 0.00%
lighttpd
4689 1 90 10 0 0 0 0 0 0.00%
fb_inet_server
3403 1 90 10 0 0 0 0 0 0.00%
fb_inet_server
2632 1 90 10 0 0 0 0 0 0.00%
fb_inet_server
All four top consumers is Lighttpd workers.
And as you noted, read, write, fault, total and percent are not updated
on machine with ZFS, so I can't compare it with UFS2 based machine.
Is this bug in top fixed in 8.x? Will you file a PR? (you know more
about FS related things than me :])
Miroslav Lachman
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