[sheepdog] [PATCH 2/2] sheep: cleaning vdi deletion process, round 2

[Hitoshi Mitake]

At Tue, 28 Jan 2014 12:41:02 +0900,
Hitoshi Mitake wrote:
> 
> At Tue, 28 Jan 2014 11:11:49 +0800,
> Liu Yuan wrote:
> > 
> > On Tue, Jan 28, 2014 at 11:38:22AM +0900, Hitoshi Mitake wrote:
> > > This patch cleans the vdi deletion process of sheep. Current vdi
> > > deletion code creates one work for one deletion. It seems that there
> > > is no reason to create so many work. This patch lets the code to
> > > create only one work for vdi deletion request.
> > 
> > why not? For now our deletion is very slow already, there are cases that
> > multiple deletion requests will be issued by users. With your patch, concurrent
> > deletions will be plainly slow to users.
> 
> The patch doesn't affect the performance of deletion. Because the
> deletion workqueue is an ordered one.
> 
> Quoting from create_work_queues():
> 	sys->deletion_wqueue = create_ordered_work_queue("deletion");

In addition, the vdi deletion work produces its successor at the end
of its process. Current code doesn't have parallelism. So I think this
patch doesn't harm performance.

I don't know why current vdi deletion process is doing such a tricky
work...

Thanks,
Hitoshi