2.6.11: iostat values broken ?

[Miquel van Smoorenburg]

I just upgrades one of our newsservers from 2.6.9 to 2.6.11. I
use "iostat -k -x 2" to see live how busy the disks are. But
I don't believe that Linux optimizes things so much that a disk
can be 1849.55% busy :)

(you'll have to stretch out your xterm to be able to read this):

Device:    rrqm/s wrqm/s   r/s   w/s  rsec/s  wsec/s    rkB/s    wkB/s avgrq-sz avgqu-sz   await  svctm  %util
hda          0.00  50.00  0.00 18.18    0.00  545.45     0.00   272.73    30.00     2.35  129.00  86.25 156.82
hdc          0.00  45.45 77.27 31.82 3927.27  618.18  1963.64   309.09    41.67     6.27   57.42  38.42 419.09
hdd          4.55   0.00 63.64  0.00   68.18    0.00    34.09     0.00     1.07     1.11   17.43  17.43 110.91
hde        477.27   0.00 45.45  0.00  522.73    0.00   261.36     0.00    11.50     0.40    8.90   8.90  40.45
hdg         18.18 70154.55 22.73 172.73   40.91 70727.27    20.45 35363.64   362.07  1010.36 1127.72  94.63 1849.55

With 2.6.9, %util never came above 100% (and that was indeed "fully loaded".
I have systems with a comparable load running 2.6.10 and 2.6.11-rc3-bk4
that also don't show this behaviour (but those are SCSI, not IDE).

I use CFQ, but changing that to deadline doesn't make a difference.

Mike.

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