Re: [dm-devel] [PATCH 07/11] [dm-thin] Commit every second to prevent too much of a position building up.

[Joe Thornber <thornber redhat com>]

On Tue, Feb 07, 2012 at 11:53:25AM -0500, Mike Snitzer wrote:
> Shouldn't this be:
> 
> 	if (bio_list_empty(&bios) || !need_commit_due_to_time(pool))
> 		return;
> 
> ?

I don't think so.  It's saying 'if <there's no reason to commit>'.  The reasons to commit are bios being non-empty or need_commit_due_to_time.

reason to commit = !bio_list_empty(&bios) || need_commit_due_to_time(pool)
!reason_to_commit = !(!bio_list_empty(&bios) || need_commit_due_to_time(pool))
!reason_to_commit = (bio_list_empty(&bios) && !need_commit_due_to_time(pool))

Agree?

> Also, should we make the commit interval tunable (akin to ext[34]'s
> 'commit' mount option)?  Or did you defer doing so until it proves
> worthwhile?

y, tunable is on the list.  Every second will do for now though.

- Joe