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Commit 5117f45d authored by Mel Gorman's avatar Mel Gorman Committed by Linus Torvalds
Browse files

page allocator: calculate the preferred zone for allocation only once 



get_page_from_freelist() can be called multiple times for an allocation.
Part of this calculates the preferred_zone which is the first usable zone
in the zonelist but the zone depends on the GFP flags specified at the
beginning of the allocation call.  This patch calculates preferred_zone
once.  It's safe to do this because if preferred_zone is NULL at the start
of the call, no amount of direct reclaim or other actions will change the
fact the allocation will fail.

[akpm@linux-foundation.org: remove (void) casts]
Signed-off-by: default avatarMel Gorman <mel@csn.ul.ie>
Reviewed-by: default avatarKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: default avatarPekka Enberg <penberg@cs.helsinki.fi>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Dave Hansen <dave@linux.vnet.ibm.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 49255c61

mm/page_alloc.c

+32 −22
Original line number Diff line number Diff line
@@ -1388,26 +1388,21 @@ static void zlc_mark_zone_full(struct zonelist *zonelist, struct zoneref *z) 
 */

static struct page *

get_page_from_freelist(gfp_t gfp_mask, nodemask_t *nodemask, unsigned int order,

		struct zonelist *zonelist, int high_zoneidx, int alloc_flags)

		struct zonelist *zonelist, int high_zoneidx, int alloc_flags,

		struct zone *preferred_zone)

{

	struct zoneref *z;

	struct page *page = NULL;

	int classzone_idx;

	struct zone *zone, *preferred_zone;

	struct zone *zone;

	nodemask_t *allowednodes = NULL;/* zonelist_cache approximation */

	int zlc_active = 0;		/* set if using zonelist_cache */

	int did_zlc_setup = 0;		/* just call zlc_setup() one time */



	(void)first_zones_zonelist(zonelist, high_zoneidx, nodemask,

							&preferred_zone);

	if (!preferred_zone)

		return NULL;



	classzone_idx = zone_idx(preferred_zone);



	if (WARN_ON_ONCE(order >= MAX_ORDER))

		return NULL;



	classzone_idx = zone_idx(preferred_zone);

zonelist_scan:

	/*

	 * Scan zonelist, looking for a zone with enough free.
@@ -1500,7 +1495,7 @@ should_alloc_retry(gfp_t gfp_mask, unsigned int order, 
static inline struct page *

__alloc_pages_may_oom(gfp_t gfp_mask, unsigned int order,

	struct zonelist *zonelist, enum zone_type high_zoneidx,

	nodemask_t *nodemask)

	nodemask_t *nodemask, struct zone *preferred_zone)

{

	struct page *page;
@@ -1517,7 +1512,8 @@ __alloc_pages_may_oom(gfp_t gfp_mask, unsigned int order, 
	 */

	page = get_page_from_freelist(gfp_mask|__GFP_HARDWALL, nodemask,

		order, zonelist, high_zoneidx,

		ALLOC_WMARK_HIGH|ALLOC_CPUSET);

		ALLOC_WMARK_HIGH|ALLOC_CPUSET,

		preferred_zone);

	if (page)

		goto out;
@@ -1537,7 +1533,8 @@ __alloc_pages_may_oom(gfp_t gfp_mask, unsigned int order, 
static inline struct page *

__alloc_pages_direct_reclaim(gfp_t gfp_mask, unsigned int order,

	struct zonelist *zonelist, enum zone_type high_zoneidx,

	nodemask_t *nodemask, int alloc_flags, unsigned long *did_some_progress)

	nodemask_t *nodemask, int alloc_flags, struct zone *preferred_zone,

	unsigned long *did_some_progress)

{

	struct page *page = NULL;

	struct reclaim_state reclaim_state;
@@ -1569,7 +1566,8 @@ __alloc_pages_direct_reclaim(gfp_t gfp_mask, unsigned int order, 


	if (likely(*did_some_progress))

		page = get_page_from_freelist(gfp_mask, nodemask, order,

					zonelist, high_zoneidx, alloc_flags);

					zonelist, high_zoneidx,

					alloc_flags, preferred_zone);

	return page;

}
@@ -1589,13 +1587,14 @@ is_allocation_high_priority(struct task_struct *p, gfp_t gfp_mask) 
static inline struct page *

__alloc_pages_high_priority(gfp_t gfp_mask, unsigned int order,

	struct zonelist *zonelist, enum zone_type high_zoneidx,

	nodemask_t *nodemask)

	nodemask_t *nodemask, struct zone *preferred_zone)

{

	struct page *page;



	do {

		page = get_page_from_freelist(gfp_mask, nodemask, order,

			zonelist, high_zoneidx, ALLOC_NO_WATERMARKS);

			zonelist, high_zoneidx, ALLOC_NO_WATERMARKS,

			preferred_zone);



		if (!page && gfp_mask & __GFP_NOFAIL)

			congestion_wait(WRITE, HZ/50);
@@ -1618,7 +1617,7 @@ void wake_all_kswapd(unsigned int order, struct zonelist *zonelist, 
static inline struct page *

__alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,

	struct zonelist *zonelist, enum zone_type high_zoneidx,

	nodemask_t *nodemask)

	nodemask_t *nodemask, struct zone *preferred_zone)

{

	const gfp_t wait = gfp_mask & __GFP_WAIT;

	struct page *page = NULL;
@@ -1668,7 +1667,8 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, 
	 * See also cpuset_zone_allowed() comment in kernel/cpuset.c.

	 */

	page = get_page_from_freelist(gfp_mask, nodemask, order, zonelist,

						high_zoneidx, alloc_flags);

						high_zoneidx, alloc_flags,

						preferred_zone);

	if (page)

		goto got_pg;
@@ -1678,7 +1678,7 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, 
		/* Do not dip into emergency reserves if specified */

		if (!(gfp_mask & __GFP_NOMEMALLOC)) {

			page = __alloc_pages_high_priority(gfp_mask, order,

				zonelist, high_zoneidx, nodemask);

				zonelist, high_zoneidx, nodemask, preferred_zone);

			if (page)

				goto got_pg;

		}
@@ -1695,7 +1695,8 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, 
	page = __alloc_pages_direct_reclaim(gfp_mask, order,

					zonelist, high_zoneidx,

					nodemask,

					alloc_flags, &did_some_progress);

					alloc_flags, preferred_zone,

					&did_some_progress);

	if (page)

		goto got_pg;
@@ -1707,7 +1708,7 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, 
		if ((gfp_mask & __GFP_FS) && !(gfp_mask & __GFP_NORETRY)) {

			page = __alloc_pages_may_oom(gfp_mask, order,

					zonelist, high_zoneidx,

					nodemask);

					nodemask, preferred_zone);

			if (page)

				goto got_pg;
@@ -1752,6 +1753,7 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order, 
			struct zonelist *zonelist, nodemask_t *nodemask)

{

	enum zone_type high_zoneidx = gfp_zone(gfp_mask);

	struct zone *preferred_zone;

	struct page *page;



	lockdep_trace_alloc(gfp_mask);
@@ -1769,11 +1771,19 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order, 
	if (unlikely(!zonelist->_zonerefs->zone))

		return NULL;



	/* The preferred zone is used for statistics later */

	first_zones_zonelist(zonelist, high_zoneidx, nodemask, &preferred_zone);

	if (!preferred_zone)

		return NULL;



	/* First allocation attempt */

	page = get_page_from_freelist(gfp_mask|__GFP_HARDWALL, nodemask, order,

			zonelist, high_zoneidx, ALLOC_WMARK_LOW|ALLOC_CPUSET);

			zonelist, high_zoneidx, ALLOC_WMARK_LOW|ALLOC_CPUSET,

			preferred_zone);

	if (unlikely(!page))

		page = __alloc_pages_slowpath(gfp_mask, order,

				zonelist, high_zoneidx, nodemask);

				zonelist, high_zoneidx, nodemask,

				preferred_zone);



	return page;

}