The patch titled
page allocator: use allocation flags as an index to the zone watermark
has been added to the -mm tree. Its filename is
page-allocator-use-allocation-flags-as-an-index-to-the-zone-watermark.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find
out what to do about this
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: page allocator: use allocation flags as an index to the zone watermark
From: Mel Gorman <mel@xxxxxxxxx>
ALLOC_WMARK_MIN, ALLOC_WMARK_LOW and ALLOC_WMARK_HIGH determin whether
pages_min, pages_low or pages_high is used as the zone watermark when
allocating the pages. Two branches in the allocator hotpath determine
which watermark to use. This patch uses the flags as an array index and
places the three watermarks in a union with an array so it can be offset.
This means the flags can be used as an array index and reduces the
branches taken.
Signed-off-by: Mel Gorman <mel@xxxxxxxxx>
Reviewed-by: Christoph Lameter <cl@xxxxxxxxxxxxxxxxxxxx>
Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
Cc: Pekka Enberg <penberg@xxxxxxxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Nick Piggin <nickpiggin@xxxxxxxxxxxx>
Cc: Dave Hansen <dave@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/mmzone.h | 8 +++++++-
mm/page_alloc.c | 20 ++++++++++----------
2 files changed, 17 insertions(+), 11 deletions(-)
diff -puN include/linux/mmzone.h~page-allocator-use-allocation-flags-as-an-index-to-the-zone-watermark include/linux/mmzone.h
--- a/include/linux/mmzone.h~page-allocator-use-allocation-flags-as-an-index-to-the-zone-watermark
+++ a/include/linux/mmzone.h
@@ -275,7 +275,13 @@ struct zone_reclaim_stat {
struct zone {
/* Fields commonly accessed by the page allocator */
- unsigned long pages_min, pages_low, pages_high;
+ union {
+ struct {
+ unsigned long pages_min, pages_low, pages_high;
+ };
+ unsigned long pages_mark[3];
+ };
+
/*
* We don't know if the memory that we're going to allocate will be freeable
* or/and it will be released eventually, so to avoid totally wasting several
diff -puN mm/page_alloc.c~page-allocator-use-allocation-flags-as-an-index-to-the-zone-watermark mm/page_alloc.c
--- a/mm/page_alloc.c~page-allocator-use-allocation-flags-as-an-index-to-the-zone-watermark
+++ a/mm/page_alloc.c
@@ -1154,10 +1154,15 @@ failed:
return NULL;
}
-#define ALLOC_NO_WATERMARKS 0x01 /* don't check watermarks at all */
-#define ALLOC_WMARK_MIN 0x02 /* use pages_min watermark */
-#define ALLOC_WMARK_LOW 0x04 /* use pages_low watermark */
-#define ALLOC_WMARK_HIGH 0x08 /* use pages_high watermark */
+/* The WMARK bits are used as an index zone->pages_mark */
+#define ALLOC_WMARK_MIN 0x00 /* use pages_min watermark */
+#define ALLOC_WMARK_LOW 0x01 /* use pages_low watermark */
+#define ALLOC_WMARK_HIGH 0x02 /* use pages_high watermark */
+#define ALLOC_NO_WATERMARKS 0x04 /* don't check watermarks at all */
+
+/* Mask to get the watermark bits */
+#define ALLOC_WMARK_MASK (ALLOC_NO_WATERMARKS-1)
+
#define ALLOC_HARDER 0x10 /* try to alloc harder */
#define ALLOC_HIGH 0x20 /* __GFP_HIGH set */
#define ALLOC_CPUSET 0x40 /* check for correct cpuset */
@@ -1445,12 +1450,7 @@ zonelist_scan:
if (!(alloc_flags & ALLOC_NO_WATERMARKS)) {
unsigned long mark;
- if (alloc_flags & ALLOC_WMARK_MIN)
- mark = zone->pages_min;
- else if (alloc_flags & ALLOC_WMARK_LOW)
- mark = zone->pages_low;
- else
- mark = zone->pages_high;
+ mark = zone->pages_mark[alloc_flags & ALLOC_WMARK_MASK];
if (!zone_watermark_ok(zone, order, mark,
classzone_idx, alloc_flags)) {
if (!zone_reclaim_mode ||
_
Patches currently in -mm which might be from mel@xxxxxxxxx are
vmscan-low-order-lumpy-reclaim-also-should-use-pageout_io_sync.patch
page-allocator-replace-__alloc_pages_internal-with-__alloc_pages_nodemask.patch
page-allocator-do-not-sanity-check-order-in-the-fast-path.patch
page-allocator-do-not-sanity-check-order-in-the-fast-path-fix.patch
page-allocator-do-not-check-numa-node-id-when-the-caller-knows-the-node-is-valid.patch
page-allocator-check-only-once-if-the-zonelist-is-suitable-for-the-allocation.patch
page-allocator-break-up-the-allocator-entry-point-into-fast-and-slow-paths.patch
page-allocator-move-check-for-disabled-anti-fragmentation-out-of-fastpath.patch
page-allocator-calculate-the-preferred-zone-for-allocation-only-once.patch
page-allocator-calculate-the-preferred-zone-for-allocation-only-once-fix.patch
page-allocator-calculate-the-migratetype-for-allocation-only-once.patch
page-allocator-calculate-the-alloc_flags-for-allocation-only-once.patch
page-allocator-remove-a-branch-by-assuming-__gfp_high-==-alloc_high.patch
page-allocator-inline-__rmqueue_smallest.patch
page-allocator-inline-buffered_rmqueue.patch
page-allocator-inline-__rmqueue_fallback.patch
page-allocator-do-not-call-get_pageblock_migratetype-more-than-necessary.patch
page-allocator-do-not-disable-interrupts-in-free_page_mlock.patch
page-allocator-do-not-setup-zonelist-cache-when-there-is-only-one-node.patch
page-allocator-do-not-check-for-compound-pages-during-the-page-allocator-sanity-checks.patch
page-allocator-use-allocation-flags-as-an-index-to-the-zone-watermark.patch
page-allocator-update-nr_free_pages-only-as-necessary.patch
page-allocator-get-the-pageblock-migratetype-without-disabling-interrupts.patch
page-allocator-use-a-pre-calculated-value-instead-of-num_online_nodes-in-fast-paths.patch
page-allocator-slab-use-nr_online_nodes-to-check-for-a-numa-platform.patch
add-debugging-aid-for-memory-initialisation-problems.patch
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
