Re: large page patch (fwd) (fwd)

David Mosberger
2002-08-03T04:14:22Z

>>>>> On Fri, 2 Aug 2002 20:32:10 -0700 (PDT), Linus Torvalds <torvalds@transmeta.com> said:

>> And since superpages quickly become counter-productive in
>> tight-memory situations anyhow, this seems like a very reasonable
>> approach.

Linus> Ehh.. The only people who are _really_ asking for the
Linus> superpages want almost nothing _but_ superpages. They are
Linus> willing to use 80% of all memory for just superpages.

Linus> Yes, it's Oracle etc, and the whole point for these users is
Linus> to avoid having any OS memory allocation for these areas.

My terminology is perhaps a bit too subtle: I user "superpage"
exclusively for the case where multiple pages get coalesced into a
larger page. The "large page" ("huge page") case that you were
talking about is different, since pages never get demoted or promoted.

I wasn't disagreeing with your case for separate large page syscalls.
Those syscalls certainly simplify implementation and, as you point
out, it well may be the case that a transparent superpage scheme never
will be able to replace the former.

--david