Re: [PATCH 2/5] writeback: dirty position control

[Jan Kara <jack@suse.cz>]

On Wed 17-08-11 02:40:19, David Horner wrote:
>  I noticed a significant typo below (another of those thousand eyes,
> thanks to Jan Kara's post that started ne looking) :
> 
>  > +static unsigned long bdi_position_ratio(struct backing_dev_info *bdi,
>  > + unsigned long thresh,
> ...
>  > + * For JBOD case, bdi_thresh (not bdi_dirty!) could fluctuate up to its
>  > + * own size, so move the slope over accordingly.
>  > + */
>  > + if (unlikely(bdi_thresh > thresh))
>  > + bdi_thresh = thresh;
>  > + /*
>  > + * scale global setpoint to bdi's:  setpoint *= bdi_thresh / thresh
>  > + */
>  > + x = div_u64((u64)bdi_thresh << 16, thresh | 1);
> 
>                   ^
>  I believe should be
> 
>     x = div_u64((u64)bdi_thresh << 16, thresh + 1);
  I've noticed this as well but it's mostly a consistency issue. 'thresh'
is going to be large in practice so there's not much difference between
thresh + 1 and thresh | 1.

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