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[PATCH] memory page_alloc zonelist caching reorder structure 

Rearrange the struct members in the 'struct zonelist_cache' structure, so
as to put the readonly (once initialized) z_to_n[] array first, where it
will come right after the zones[] array in struct zonelist.

This pretty much eliminates the chance that the two frequently written
elements of 'struct zonelist_cache', the fullzones bitmap and last_full_zap
times, will end up on the same cache line as the performance sensitive,
frequently read, never (after init) written zones[] array.

Keeping frequently written data off frequently read cache lines is good for
performance.

Thanks to Rohit Seth for the suggestion.

Signed-off-by: Paul Jackson <pj@sgi.com>
Cc: Rohit Seth <rohitseth@google.com>
Cc: Paul Menage <menage@google.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Paul Jackson 2006-12-06 20:31:49 -08:00 committed by Linus Torvalds
parent 9276b1bc96
commit 7253f4ef04
1 changed files with 1 additions and 1 deletions
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2
include/linux/mmzone.h
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@ -352,8 +352,8 @@ struct zone {
struct zonelist_cache {
DECLARE_BITMAP(fullzones, MAX_ZONES_PER_ZONELIST); /* zone full? */
unsigned short z_to_n[MAX_ZONES_PER_ZONELIST]; /* zone->nid */
DECLARE_BITMAP(fullzones, MAX_ZONES_PER_ZONELIST); /* zone full? */
unsigned long last_full_zap; /* when last zap'd (jiffies) */
};
#else