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SubjectRe: [dm-devel] Re: dm-ioband: Test results.
From
Hi Vivek,

> I quickly looked at the xls sheet. Most of the test cases seem to be
> direct IO. Have you done testing with buffered writes/async writes and
> been able to provide service differentiation between cgroups?
>
> For example, two "dd" threads running in two cgroups doing writes.

Thanks for taking a look at the sheet. I did a buffered write test
with "fio." Only two "dd" threads can't generate enough I/O load to
make dm-ioband start bandwidth control. The following is a script that
I actually used for the test.

#!/bin/bash
sync
echo 1 > /proc/sys/vm/drop_caches
arg="--size=64m --rw=write --numjobs=50 --group_reporting"
echo $$ > /cgroup/1/tasks
fio $arg --name=ioband1 --directory=/mnt1 --output=ioband1.log &
echo $$ > /cgroup/2/tasks
fio $arg --name=ioband2 --directory=/mnt2 --output=ioband2.log &
echo $$ > /cgroup/tasks
wait

I created two dm-devices to easily monitor the throughput of each
cgroup by iostat, and gave weights of 200 for cgroup1 and 100 for
cgroup2 that means cgroup1 can use twice bandwidth of cgroup2. The
following is a part of the output of iostat. dm-0 and dm-1 corresponds
to ioband1 and ioband2. You can see the bandwidth is according to the
weights.

avg-cpu: %user %nice %system %iowait %steal %idle
0.99 0.00 6.44 92.57 0.00 0.00

Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn
dm-0 3549.00 0.00 28392.00 0 28392
dm-1 1797.00 0.00 14376.00 0 14376

avg-cpu: %user %nice %system %iowait %steal %idle
1.01 0.00 4.02 94.97 0.00 0.00

Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn
dm-0 3919.00 0.00 31352.00 0 31352
dm-1 1925.00 0.00 15400.00 0 15400

avg-cpu: %user %nice %system %iowait %steal %idle
0.00 0.00 5.97 94.03 0.00 0.00

Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn
dm-0 3534.00 0.00 28272.00 0 28272
dm-1 1773.00 0.00 14184.00 0 14184

avg-cpu: %user %nice %system %iowait %steal %idle
0.50 0.00 6.00 93.50 0.00 0.00

Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn
dm-0 4053.00 0.00 32424.00 0 32424
dm-1 2039.00 8.00 16304.00 8 16304

Thanks,
Ryo Tsuruta


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