RBD stall when creating and listing images

[Wido den Hollander <wido@widodh.nl>]

Hi,

I was just playing with my libvirt driver and I noticed a stall.

On one host I had running:

for i in {0..8192}; do rbd create --size 64 image-$i; echo "created 
image-$i"; done

And on the other host I was running a pool-refresh in libvirt.

As I was tailing the libvirt log I noticed that it had stalled, so I 
checked my other terminal and saw that the creation of new images had 
also stalled.

This situation persisted for about ~20 seconds and then everything 
started to continue.

At the moment of the stall libvirt was calling rbd_list and was not 
doing any rbd_stat yet.

I'm trying to reproduce it here, but I wonder if there is a logical 
explanation for this situation?

I'm running 0.44 on my cluster and 0.45 on the client btw.

Wido