Re: [RFC 0/3] Recursive reclaim (on __PF_MEMALLOC)

Christoph Lameter
2007-08-14T15:29:29Z

On Tue, 14 Aug 2007, Peter Zijlstra wrote:

> On Tue, 2007-08-14 at 07:21 -0700, Christoph Lameter wrote:
> > The following patchset implements recursive reclaim. Recursive reclaim
> > is necessary if we run out of memory in the writeout patch from reclaim.
> >
> > This is f.e. important for stacked filesystems or anything that does
> > complicated processing in the writeout path.
> >
> > Recursive reclaim works because it limits itself to only reclaim pages
> > that do not require writeout. It will only remove clean pages from the LRU.
> > The dirty throttling of the VM during regular reclaim insures that the amount
> > of dirty pages is limited.
>
> No it doesn't. All memory can be tied up by anonymous pages - who are
> dirty by definition and are not clamped by the dirty limit.

Ok but that could be addressed by making sure that a certain portion of
memory is reserved for clean file backed pages.