Re: block: eliminate ELEVATOR_INSERT_REQUEUE

[Mike Snitzer <snitzer@redhat.com>]

On Tue, Mar 29 2011 at  7:56am -0400,
Jens Axboe <axboe@kernel.dk> wrote:

> On 2011-03-29 00:15, Mike Snitzer wrote:
> > On Mon, Mar 28 2011 at  4:23am -0400,
> > Tejun Heo <tj@kernel.org> wrote:
> > 
> >> On Sat, Mar 26, 2011 at 12:21:56AM -0400, Mike Snitzer wrote:
> >>> Should blk_kick_flush() process the flush request without calling
> >>> elv_insert() -- like is done with open coded list_add() in
> >>> blk_insert_flush()?
> >>>
> >>> Or should blk_insert_flush() use elv_insert() with
> >>> ELEVATOR_INSERT_REQUEUE too? 
> >>
> >> Hmmm... I would prefer the latter.  Given that INSERT_REQUEUE and
> >> FRONT are no longer different, it would probably be better to use
> >> FRONT tho.  The only reason REQUEUE is used there is to avoid kicking
> >> the queue from elv_insert(), which is gone now.
> > 
> > OK, I came up with the following patch.
> > 
> > Jens, this is just a natural cleanup given the code that resulted from
> > the flush-merge and onstack plugging changes coming together.
> 
> That looks nice and clean. What kind of testing has been done?

I successfully tested it with that fsync-heavy ffsb workload (xfs on
mpath device).

Mike