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From: David Mosberger <davidm@napali.hpl.hp.com>
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Date: Mon, 5 Aug 2002 22:19:24 -0700
To: "David S. Miller" <davem@redhat.com>
Cc: davidm@hpl.hp.com, rohit.seth@intel.com, frankeh@watson.ibm.com,
       torvalds@transmeta.com, gh@us.ibm.com, Martin.Bligh@us.ibm.com,
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Subject: Re: large page patch (fwd) (fwd)
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>>>>> On Mon, 05 Aug 2002 21:58:17 -0700 (PDT), "David S. Miller" <davem@redhat.com> said:

  >>    From: David Mosberger <davidm@napali.hpl.hp.com> 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
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