> > > <snip>
> > >
> > > > struct scan_control *sc)
> > > > {
> > > > + enum bdi_queue_status ret = QUEUEWRITE_DENIED;
> > > > +
> > > > if (current->flags & PF_SWAPWRITE)
> > > > - return 1;
> > > > + return QUEUEWRITE_ALLOWED;
> > > > if (!bdi_write_congested(bdi))
> > > > - return 1;
> > > > + return QUEUEWRITE_ALLOWED;
> > > > + else
> > > > + ret = QUEUEWRITE_CONGESTED;
> > > > if (bdi == current->backing_dev_info)
> > > > - return 1;
> > > > + return QUEUEWRITE_ALLOWED;
> > > >
> > > > /* lumpy reclaim for hugepage often need a lot of write */
> > > > if (sc->order > PAGE_ALLOC_COSTLY_ORDER)
> > > > - return 1;
> > > > - return 0;
> > > > + return QUEUEWRITE_ALLOWED;
> > > > + return ret;
> > > > }
> > >
> > > The function can't return QUEUEXXX_DENIED.
> > > It can affect disable_lumpy_reclaim.
> > >
> >
> > Yes, but that change was made in "vmscan: Narrow the scenarios lumpy
> > reclaim uses synchrounous reclaim". Maybe I am misunderstanding your
> > objection.
>
> I means current may_write_to_queue never returns QUEUEWRITE_DENIED.
> What's the role of it?
>
As of now, little point because QUEUEWRITE_CONGESTED implies denied. I was allowing
the possibility of distinguishing between these cases in the future depending
on what happened with wait_iff_congested(). I will drop it for simplicity
and reintroduce it when or if there is a distinction between
denied and congested.
> In addition, we don't need disable_lumpy_reclaim_mode() in pageout.
> That's because both PAGE_KEEP and PAGE_KEEP_CONGESTED go to keep_locked
> and calls disable_lumpy_reclaim_mode at last.
>
True, good spot.
--
Mel Gorman
Part-time Phd Student Linux Technology Center
University of Limerick IBM Dublin Software Lab
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