Re: swapout selection change in pre1

[Jamie Lokier <lk@tantalophile.demon.co.uk>]

Linus Torvalds wrote:
> It's just fairly slow to look things up that way. That's going to be
> especially true of you have _lots_ of people mapping that vma - you'd have
> to look them all up, even if only one or two actually have the page in
> question mapped.
>
> (The alternative, of course, is to add a new "struct list_head" to the
> "struct page" structure, and make that be the anchor for all VMA's that
> have this page actually inserted. That would be pretty efficient, but I'd
> hate wasting the memory, ugh. We could be clever and share a list for
> multiple pages, ho humm..)

I don't see how you can anchor "all VMAs that have this page actually
inserted".  That's a list per page.  Where do all the links live
(without using tons of memory)?

But anyway, as long as you can arrange that a page is hooked into a list
of regions, using region splitting, where on average at least X% of the
regions have the page mapped, that should be ok.

-- Jamie
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