Re: new OOM heuristic failure (was: Re: VM: qsbench)

[torvalds@transmeta.com (Linus Torvalds)]

In article <20011031184256.6e541e43.skraw@ithnet.com>,
Stephan von Krawczynski  <skraw@ithnet.com> wrote:
>
>I took a deep look into this code and wonder how this benchmark manages to get
>killed. If I read that right this would imply that shrink_cache has run a
>hundred times through the _complete_ inactive_list finding no free-able pages,
>with one exception that I read across:

That's a red herring. The real reason it is killed is that the machine
really _is_ out of memory, but that, in turn, is because the swap space
is totally filled up - with pages we have in memory in the swap cache.

The swap cache is wonderful for many thing, but Linux has historically
had swap as "additional" memory, and the swap cache really really wants
to have backing store for the _whole_ working set, not just for the
pages we have to get rid of.

Thus the two-line patch elsewhere in this thread, which says "ok, if
we're low on swap space, let's start decimating the swap cache entries
for stuff we have in memory". 

		Linus