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SubjectRe: 2.4.8/2.4.9 VM problems

~
On Mon, 20 Aug 2001, Daniel Phillips wrote:

> On August 20, 2001 09:12 pm, Marcelo Tosatti wrote:
> > On Mon, 20 Aug 2001, Daniel Phillips wrote:
> > > On August 20, 2001 09:14 pm, Mike Galbraith wrote:
> > > > We need to get the pages 'actioned' (the only thing that really matters)
> > > > off of the dirty list so that they are out of the equation.. that I'm
> > > > sure of.
> > >
> > > Well, except when the page is only going to be used once, or not at all (in
> > > the case of an unused readahead page). Otherwise, no, we don't want to have
> > > frequently used pages or pages we know nothing about dropping of the inactive
> > > queue into the bit-bucket. There's more work to do to make that come true.
> >
> > Find riel's message with topic "VM tuning" to linux-mm, then take a look
> > at the 4th aging option.
> >
> > That one _should_ be able to make us remove all kinds of "hacks" to do
> > drop behind, and also it should keep hot/warm active memory _in cache_
> > for more time.
>
> I looked at it yesterday. The problem is, it loses the information about *how*
> a page is used: pagecache lookup via readahead has different implications than
> actual usage. The other thing that looks a little problematic, which Rik also
> pointed out, is the potential long lag before the inactive page is detected.
> A lot of IO can take place in this time, filling up the active list with pages
> that we could have evicted much earlier.

We're using unlazy page activation on -ac so that is not an issue.


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