Re: [Patch 1/3] Reclaim pmd and pte entries to quicklists.

From: David Mosberger <davidm_at_napali.hpl.hp.com>
Date: 2005-03-02 06:23:21
>>>>> On Sat, 26 Feb 2005 08:25:41 -0600, Robin Holt <holt@sgi.com> said:

  Robin> Tony, This patch introduces using the quicklists for pgd,
  Robin> pmd, and pte levels by combining the alloc and free functions
  Robin> into a common set of routines.  This greatly simplifies the
  Robin> reading of this header file.

Agreed, but now you implicitly assume that the directories at all
levels are the same size.  I think it would be better to pass the
desired size to the alloc routine such that you can at least fail
noisily if somebody ever tried to use different-size directories.

  Robin> Before:
  Robin> Process fork+exit: 255.0909 microseconds

  Robin> After:
  Robin> Process fork+exit: 184.2333 microseconds

Nice.

  Robin> +	ret = local_cpu_data->pgtable_quicklist;

Is there any reason pgtable_quicklist isn't a normal per-CPU variable?
We didn't use to have that facility, that's why we used to keep it in
local_cpu_data, but noadays, there should be no need for that ugly
hack.

Since this is performance-critical, it's probably worthwhile to use
__ia64_per_cpu_var() to access the quicklist.  That way, the address
of pgtable_quicklist can be obtained with a single "addl" instruction.

	--david


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Received on Tue Mar 1 14:23:39 2005

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