Zone padding separates write-intensive fields used by page allocation,
compaction and vmstats but the comments are a little misleading and
need clarification.
Signed-off-by: Mel Gorman <mgor...@techsingularity.net>
---
include/linux/mmzone.h | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index d4f5cac0a8c3..edafdaf62e90 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -477,20 +477,21 @@ struct zone {
unsigned long wait_table_hash_nr_entries;
unsigned long wait_table_bits;
+ /* Write-intensive fields used from the page allocator */
ZONE_PADDING(_pad1_)
+
/* free areas of different sizes */
struct free_area free_area[MAX_ORDER];
/* zone flags, see below */
unsigned long flags;
- /* Write-intensive fields used from the page allocator */
+ /* Primarily protects free_area */
spinlock_t lock;
+ /* Write-intensive fields used by compaction and vmstats. */
ZONE_PADDING(_pad2_)
- /* Write-intensive fields used by page reclaim */
-
/*
* When free pages are below this point, additional steps are taken
* when reading the number of free pages to avoid per-cpu counter
--
2.6.4
