Re: [PATCH] Do not delete cgroups upon completion of fio job

[Vivek Goyal <vgoyal@redhat.com>]

On Wed, Mar 31, 2010 at 07:26:00PM +0200, Jens Axboe wrote:
> On Wed, Mar 31 2010, Vivek Goyal wrote:
> > Currently upon fio job completion, we delete the cgroups. But in the
> > process we also loose important debugging information presetn in cgroup
> > files. For example time information in blkio.time, sector information in
> > blkio.sectors and how many a times a group was dequeued blkio.dequeue.
> > Leaving the cgroups as it is, allows one to go and inspect those files
> > after the fio job is complete.
> > 
> > Secondly, cgroups might have already been created by user before fio job
> > started. In that case it is not very right to delete cgroups after job
> > completion.
> 
> Confused, I was pretty sure that I added code back then to only delete
> cgroups when they were created by fio. Checking, that is what it should
> do - we only add the cgroup to the kill list, if we were the one to
> create it. That was on purpose, since I did not want to leave them
> around.

Sorry, I did not check properly. Upon retest, I see cgroups are not being 
deleted if these were not created by fio.

> 
> I'd suggest adding a specific option to NOT kill a cgroup. Or you could
> have a post_exec option that tar's up the contents of that directory,
> perhaps even formalized?

I think adding an option to not kill a cgroup looks good to me as I don't
have to do some more scripting to tar and then untar and read cgroup debug
files. 

I will send a patch for that option.

Thanks
Vivek