Re: [PATCH -mm] throttle direct reclaim when too many pages are isolatedalready (v3)

[Rik van Riel]

Pavel Machek wrote:
> On Wed 2009-07-15 23:53:18, Rik van Riel wrote:
> > When way too many processes go into direct reclaim, it is possible
> > for all of the pages to be taken off the LRU.  One result of this
> > is that the next process in the page reclaim code thinks there are
> > no reclaimable pages left and triggers an out of memory kill.
> >
> > One solution to this problem is to never let so many processes into
> > the page reclaim path that the entire LRU is emptied.  Limiting the
> > system to only having half of each inactive list isolated for
> > reclaim should be safe.
>
> Is this still racy? Like on 100cpu machine, with LRU size of 50...?

If a 100 CPU system gets down to just 100 reclaimable pages,
getting the OOM killer to trigger sounds desirable.

The goal of this patch is to avoid _false_ OOM kills, when
the system still has enough reclaimable memory available.

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