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Date: Mon, 9 Aug 2004 10:46:16 -0700
From: "David S. Miller" <davem@redhat.com>
Subject: Re: copy_page_range()
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On Mon, 9 Aug 2004 02:27:16 -0700
David Mosberger <davidm@napali.hpl.hp.com> wrote:

> >>>>> On Mon, 9 Aug 2004 02:04:58 -0700, William Lee Irwin III <wli@holomorphy.com> said:
> 
>   William> These results are actually consistent with large-memory
>   William> ia32.  Instruction-level profiles showed that the largest
>   William> overhead in copy_page_range() on such ia32 boxen appeared
>   William> to be mm->rss++.
> 
> Hmmh, for me, the single biggest stall seems to come from the pmd_none()
> check in free_one_pmd().

Right, that is what gets hit on sparc64 too.

On ia32, the tables are half the size, thus half the amount of
memory accesses per table traversal.