[Users] iopslimit

[Kristian Marcroft]

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Dear List,

we are currently testing a Node that has SSDs built in.

We have some really nice results when not setting any iopslimits or
iolimits.

For some reason though, if we do set the iopslimit, these do not seem
to take any effect or at least not the right effect.

Setting up an iopslimit of 500, actually limits the iops at 500.
This is expected behaviour.

Setting a limit of 2500 iops, however seems to limit the iops at
around about 30k iops?

Initially we started at setting iopslimit at 15000, which seemed to
have absolutely no effect, as the measured iops where at 137000 iops.

The command used for all tests within a CT was:

# fio --name=global --rw=read --size=16G --name=job1 --name=job2

Used Kernel Version: 2.6.32-042stab103.6
Used vzctl Version: vzctl-4.8-1.x86_64
Used ploop Version: ploop-1.12.2-1.x86_64

Can anyone explain this behaviour or give further advice on how to
proceed in setting an iopslimit of 15000 and actually having it
limited to 15000 iops?

Looking forward to your reply.

Regards,
Kristian Marcroft
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