Re: large page patch (fwd) (fwd)

[David Mosberger]

>>>>> On Mon, 05 Aug 2002 21:58:17 -0700 (PDT), "David S. Miller" <[e-mail]> said:

  >>    From: David Mosberger <[e-mail]> Date:
  >> Mon, 5 Aug 2002 22:01:16 -0700

  >>    In my opinion, this is perhaps the strongest argument
  >> *for* a separate "giant page" syscall interface.  It will be
  >> very hard (perhaps impossible) to optimize superpages to work
  >> efficiently when the ratio of superpage/basepage grows huge
  >> (as, by definition, the kernel would manage them as a set of
  >> basepages).

  DaveM> Actually, this is one of the reasons there was a lot of
  DaveM> research into using sub-page clustering for large mappings in
  DaveM> the TLB.  Basically how this worked is that for a superpage,
  DaveM> you could stick multiple sub-mappings into the entry such
  DaveM> that you didn't need a fully physically contiguous superpage.

Sounds great if you have the hardware that can do it.  Not too many
CPUs I know of support it.

	--david