Re: [PATCH 1/2] writeback: Improve busyloop prevention

[Jan Kara <jack@suse.cz>]

On Thu 08-09-11 08:57:50, Wu Fengguang wrote:
> On Thu, Sep 08, 2011 at 08:44:43AM +0800, Jan Kara wrote:
> > Writeback of an inode can be stalled by things like internal fs locks being
> > held. So in case we didn't write anything during a pass through b_io list,
> > just wait for a moment and try again.
>  
> Reviewed-by: Wu Fengguang <fengguang.wu@intel.com>
> 
> with comments below.
> 
> > +		trace_writeback_wait(wb->bdi, work);
> > +		spin_unlock(&wb->list_lock);
> 
> __set_current_state(TASK_INTERRUPTIBLE);
  Ah, right. Thanks for catching this.
> 
> > +		schedule_timeout(pause);
> 
> > +		pause <<= 1;
> > +		if (pause > HZ / 10)
> > +			pause = HZ / 10;
> 
> It's a bit more safer to do
> 
>                 if (pause < HZ / 10)
>                         pause <<= 1;
> 
> in case someone hacked HZ=1.
  Good idea. Done. Thanks for review.

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