Re: page_launder() bug

Rik van Riel
2001-05-13T19:39:43Z

On Sun, 13 May 2001, Linus Torvalds wrote:
> On Sun, 13 May 2001, Rik van Riel wrote:
> >
> > Why the hell would we want this ?
> You've missed about half the discussion, it seems..

True, I was away at a conference ;)

> > If the page is referenced, it should be moved back to the
> > active list and should never be a candidate for writeout.
>
> Wrong.
>
> There are
> (a) dead swap pages, where it doesn't matter one _whit_ whether it is
> referenced or not, because we know with 100% certainty that nobody
> will ever reference it again. This _may_ be true in other cases too,
> but we know it is true for swap pages that have lost all references.
> (b) filesystems and memory allocators that might want to get feedback on
> the fact that we're even _looking_ at their pages, and that we're
> aging them down. They might easily use these things for starting
> background activity like deciding to close the logs..
>
> The high-level VM layer simply doesn't have that kind of information.

Agreed. I'd like to make sure, however, that we keep the
high-level VM cleanly separated from the lower layers so
we can keep the VM maintainable and predictable...

regards,

Rik
--
Virtual memory is like a game you can't win;
However, without VM there's truly nothing to lose...

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