On Wed, Jan 05, 2022 at 04:01:07PM -0800, Darrick J. Wong wrote:
> On Thu, Jan 06, 2022 at 09:48:29AM +1100, Dave Chinner wrote:
> > +
> > + might_sleep();
> >
> > list_replace_init(&ioend->io_list, &tmp);
> > + segments = ioend->io_segments;
> > iomap_finish_ioend(ioend, error);
> >
> > while (!list_empty(&tmp)) {
> > + if (segments > 32768) {
> > + cond_resched();
> > + segments = 0;
> > + }
> > ioend = list_first_entry(&tmp, struct iomap_ioend, io_list);
> > list_del_init(&ioend->io_list);
> > + segments += ioend->io_segments;
> > iomap_finish_ioend(ioend, error);
> > }
>
> I wonder, should we take one more swing at cond_resched at the end of
> the function so that we can return to the caller having given the system
> at least one chance to reschedule?
That's for the caller of xfs_finish_ioends() to deal with as it
loops over each set of merged ioends and does it's own processing.
i.e. that's what the cond_resched() I added to the XFS endio
processing code here provides:
> > void
> > xfs_end_io(
> > struct work_struct *work)
> > @@ -157,6 +170,7 @@ xfs_end_io(
> > list_del_init(&ioend->io_list);
> > iomap_ioend_try_merge(ioend, &tmp);
> > xfs_end_ioend(ioend);
> > + cond_resched();
> > }
> > }
Cheers,
Dave.
--
Dave Chinner
david@xxxxxxxxxxxxx
