Re: [patch 1/2] x86: track memtype for RAM in page struct

From: Jeremy Fitzhardinge
Date: Sun Sep 14 2008 - 10:18:18 EST

Ingo Molnar wrote:
> * Jeremy Fitzhardinge <jeremy@xxxxxxxx> wrote:
>> Venkatesh Pallipadi wrote:
>>> From: Suresh Siddha <suresh.b.siddha@xxxxxxxxx>
>>> Subject: [patch 1/2] x86: track memtype for RAM in page struct
>>> Track the memtype for RAM pages in page struct instead of using the memtype
>>> list. This avoids the explosion in the number of entries in memtype list
>>> (of the order of 20,000 with AGP) and makes the PAT tracking simpler. We are
>>> using PG_arch_1 bit in page->flags.
>> Please define PG_arch_1 a proper name so that its easy to tell its
>> being used just by looking at page-flags.h.
> it should be defined in include/asm-x86/page.h though, not in
> page-flags.h - other architectures are using this flag for other
> purposes.

No, other shared-use flags are all defined in page-flags.h:

enum pageflags {

/* Filesystems */
PG_checked = PG_owner_priv_1,

/* XEN */
PG_pinned = PG_owner_priv_1,
PG_savepinned = PG_dirty,

/* SLOB */
PG_slob_page = PG_active,
PG_slob_free = PG_private,

/* SLUB */
PG_slub_frozen = PG_active,
PG_slub_debug = PG_error,

We could #ifdef CONFIG_X86 just to make it clear we're talking about a
specific X86 usage. But page-flags.h does seem to have become the
central authority on all struct page flags usage.

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