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

Jan Kara
2011-08-17T12:04:00Z

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