Re: [PATCH 1/3] i/o bandwidth controller documentation

[Andrea Righi]

Thanks Randy, I've applied all your fixes to my local documentation,
next patchset version will include them. A few small comments below.

Randy Dunlap wrote:
> > +* Run a benchmark doing I/O on /dev/sda1 and /dev/sda5; I/O limits and usage
> > +  defined for cgroup "foo" can be shown as following:
> > +  # cat /mnt/cgroup/foo/blockio.bandwidth
> > +  === device (8,1) ===
> > +    bandwidth limit: 1024 KiB/sec
> > +  current i/o usage: 819 KiB/sec
> > +  === device (8,5) ===
> > +    bandwidth limit: 1024 KiB/sec
> > +  current i/o usage: 3102 KiB/sec
>
> Ugh, this makes it look like the output does "pretty printing" (formatting),
> which is generally not a good idea.  Let some app be responsible for that,
> not the kernel.  Basically this means don't use leading spaces just to make the
> ":"s line up in the output.

Sounds reasonable. I think the output could be further reduced,
the following format should be explanatory enough.

device: %u,%u
bandwidth: %lu KiB/sec
usage: %lu KiB/sec

> > +WARNING: per-block device limiting rules always refer to the dev_t device
> > +number. If a block device is unplugged (i.e. a USB device) the limiting rules
> > +associated to that device persist and they are still valid if a new device is
>
> associated with (?)

what about:

...the limiting rules defined for that device...

-Andrea
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