Re: [PATCH][5/?] count writeback pages in nr_scanned

[Nick Piggin]

Andrew Morton wrote:
> Nick Piggin <nickpiggin@xxxxxxxxxxxx> wrote:
>
> > Rik van Riel wrote:
> >
> > > On Thu, 6 Jan 2005, Nick Piggin wrote:
> > >
> > >
> > > > I think what Andrea is worried about is that blk_congestion_wait is 
> > > > fairly vague, and can be a source of instability in the scanning 
> > > > implementation.
> > >
> > >
> > > The recent OOM kill problem has been happening:
> > > 1) with cache pressure on lowmem only, due to a block device write
> > > 2) with no block congestion at all
> > > 3) with pretty much all pageable lowmme pages in writeback state
> > >
> > > It appears the VM has trouble dealing with the situation where
> > > there is no block congestion to wait on...
> >
> > Try, together with your nr_scanned patch, to replace blk_congestion_wait
> > with io_schedule_timeout.
>
>
> Why?  Is the nr_scanned fix insufficient?

I thought it sounded like he implied that nr_scanned was insufficient
(otherwise he might have said "to wait on ... but my patch fixes it").


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