Re: large page patch

[David Mosberger <davidm@napali.hpl.hp.com>]

>>>>> On Thu, 01 Aug 2002 22:20:53 -0700 (PDT), "David S. Miller" <davem@redhat.com> said:

  DaveM>    From: David Mosberger <davidm@napali.hpl.hp.com> Date:
  DaveM> Thu, 1 Aug 2002 22:24:05 -0700

  DaveM>    In my opinion the proposed large-page patch addresses a
  DaveM> relatively pressing need for databases (primarily).

  DaveM> Databases want large pages with IPC_SHM, how can this
  DaveM> special syscal hack address that?

I believe the interface is OK in that regard.  AFAIK, Oracle is happy
with it.

  DaveM> It's great for experimentation, but give up syscall slots
  DaveM> for this?

I'm a bit concerned about this, too.  My preference would have been to
use the regular mmap() and shmat() syscalls with some
augmentation/hint as to what the preferred page size is (Simon
Winwood's OLS 2002 paper talks about some options here).  I like this
because hints could be useful even with a transparent superpage
scheme.

The original Intel patch did use more of a hint-like approach (the
hint was a simple binary flag though: give me regular pages or give me
large pages), but Linus preferred a separate syscall interface, so the
Intel folks switched over to doing that.

	--david
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