Re: [PATCH] cgroup: limit block I/O bandwidth

[Andrea Righi <righiandr@users.sourceforge.net>]

Jens Axboe wrote:
> Your approach is totally flawed, imho. For instance, you don't want a
> process to be able to dirty memory at foo mb/sec but only actually
> write them out at bar mb/sec.

Right. Actually my problem here is that the processes that write out
blocks are different respect to the processes that write bytes in
memory, and I would be able to add limits on those processes that are
dirtying memory.

> The noop-iosched changes are also very buggy. The queue back pointer
> breaks reference counting and the task pointer storage assumes the task
> will also always be around. That's of course not the case.

Yes, this really need a lot of fixes. I simply posted the patch to know
if such approach (in general) could have sense or not.

> IOW, you are doing this at the wrong level.
> 
> What problem are you trying to solve?

Limiting block I/O bandwidth for tasks that belong to a generic cgroup,
in order to provide a sort of a QoS on block I/O.

Anyway, I'm quite new in the wonderful land of the I/O scheduling, so
any help is appreciated.

Thanks,
-Andrea