[dm-devel] I/O block when removing thin device on the same pool

[Joe Thornber]

On Fri, Jan 22, 2016 at 02:38:28PM +0100, Lars Ellenberg wrote:
> We have seen lvremove of thin snapshots sometimes minutes,
> even ~20 minutes before.

I did some work on speeding up thin removal in autumn '14, in
particular agressively prefetching metadata pages sped up the tree
traversal hugely.  Could you confirm you're seeing pauses of this
duration with currently kernels please?

Obviously any pause, even a few seconds is unacceptable.  Having a
background kernel worker thread doing the delete, as you describe, is
the way to go.  But there are complications to do with
transactionality and crash protection that have prevented me
implementing it.  I'll think on it some more now I know it's such a
problem for you.

- Joe