Re: [PATCH 2/4] writeback: quit background/periodic work when other works are enqueued

[Jan Kara <jack@suse.cz>]

On Mon 01-11-10 20:07:33, Wu Fengguang wrote:
> On Tue, Sep 14, 2010 at 08:40:33PM +0800, Jan Kara wrote:
> > Background writeback are easily livelockable (from a definition of their
> > target). This is inconvenient because it can make sync(1) stall forever waiting
> > on its queued work to be finished. Generally, when a flusher thread has
> > some work queued, someone submitted the work to achieve a goal more specific
> > than what background writeback does. So it makes sense to give it a priority
> > over a generic page cleaning.
> > 
> > Thus we interrupt background writeback if there is some other work to do. We
> > return to the background writeback after completing all the queued work.
> > 
> >   Could you please update it? Thanks.
> > 								Honza
> > 
> > PS: I've also attached the full patch if that's more convenient for you.
> 
> You patches are more complete than mine, so let's use them. However I
> do prefer to have a standalone wb_check_background_flush() that is
> called _after_ wb_check_old_data_flush(). This helps make the writeout
> a bit more ordered and the separation itself looks a bit more clean to
> me.
> 
> Followed are the slightly updated patches. IMHO they are straightforward
> fixes that could be merged before other writeback changes.
  Yes, the updated patch looks OK to me. Thanks for picking the patches up.

									Honza
-- 
Jan Kara <jack@suse.cz>
SUSE Labs, CR

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