[dm-devel] dm-ioband max-bw and min-bw

[Степан Фёдоров <stepan fedorov clodo ru>]

Hello!

I have some questions about dm-ioband module.

My m-ioband patch version is 1.14.0 on SLES11SP1 2.6.32.29-0.3-xen kernel.

/dev/mapper/1id-22-109 is a multipath device. In normal case, block device performance test shows 500-600Mb/sec on this device.

Next i do next commands:

echo "0 $(blockdev --getsize /dev/mapper/1id-22-109) ioband /dev/mapper/1id-22-109 0 0 0 none range-bw 0 :10000:50000" |dmsetup create iob-22-109

in /dev/mapper i see iob-22-109 device. OK.

My block device performance test shows on this device about 50Mb/sec.

dmsetup table shows me:

iob-22-109: 0 10485760 ioband 253:5 0 4 192 none range-bw 12288 :10000:50000

for this device.

All this is OK, and next i want to change somthing. I do:

dmsetup message iob-22-109 0 max-bw 70000

My block device performance test shows now on this device about 500-600Mb/sec, and dmsetup table shows:

iob-22-109: 0 10485760 ioband 253:5 0 4 192 none range-bw 12288 :10000:0

As you can see - maximum bandwidth value, resets to zero after setting it to 70Mb by "dmsetup message ..." command.

If next i change min-bw by same way - it also rests to zero instead right value.

My question: is this a bug in some software, or just a result of something wrong in my actions?

Thank you!