Re: snapshot destruction making IO extremely slow

[David Sterba <dsterba@suse.cz>]

On Mon, Mar 30, 2015 at 05:09:52PM +0200, Marc Cousin wrote:
> > So it would be good to sample the active threads and see where it's
> > spending the time. It could be the somewhere in the rb-tree representing
> > extents, but that's a guess.
> > 
> I just need to be told how to do that :)
> 
> Something like a perf top ?

for i in `pgrep btrfs`; do
        ps $i
	sudo cat /proc/$i/stack 2>/dev/null
done

and capture samples every second.