Re: need help interpreting 'free' output.

[Linus Torvalds]

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On Tue, 30 Oct 2001, Hugh Dickins wrote:
>
> However, unlike 2.4.13, 2.4.14-pre (you tried pre4, I just tried pre5)
> seems much too unwilling to shrink_dcache and shrink_icache: your
> memory hog should shrink them, but it seems not to.  Linus?

Yes. It's next on my list.

My _preferred_ approach would actually be to move the slab pages to the
LRU list too, and have a special "slab" address space (we don't need to
actually hash them, we just make page->mapping point to it), and have the
cache shrink be done naturally as part of writepage().

That way "shrink_cache()" reacts very naturally to slab pressure, while
right now it's more of a random behaviour. That's what the "anonymous
pages in the LRU" approach fixes - the VM scanning reacts very naturally
(instead of with subtle tweaking and almost random behaviour) to mapped
page pressure.

The "slab address space" is a longer-range plan, though. It migth be
really simple (the writepage would just move the page to the active list
and try to shrink the slab that was hit), but I think the current stuff is
"good enough".

So in the short range, I haven't come up with any really good approaches,
but I suspect I'll just have to move the shrink_[di]cache() back to the
caller, which will at least shrink them on swapouts (a bit too much, I
think, but on the other hand maybe not).

Patch attached,

		Linus

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