From: Mel Gorman <mgorman@techsingularity.net>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Vlastimil Babka <vbabka@suse.cz>, Linux-MM <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>,
Mel Gorman <mgorman@techsingularity.net>
Subject: [PATCH 13/24] mm, page_alloc: Remove redundant check for empty zonelist
Date: Tue, 12 Apr 2016 11:12:14 +0100 [thread overview]
Message-ID: <1460455945-29644-14-git-send-email-mgorman@techsingularity.net> (raw)
In-Reply-To: <1460455945-29644-1-git-send-email-mgorman@techsingularity.net>
A check is made for an empty zonelist early in the page allocator fast
path but it's unnecessary. The check after first_zones_zonelist call
should catch that situation. Removing the first check is slower for
machines with memoryless nodes but that is a corner case that can
live with the overhead.
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
---
mm/page_alloc.c | 8 --------
1 file changed, 8 deletions(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index df03ccc7f07c..e50e754ec9eb 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3374,14 +3374,6 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order,
if (should_fail_alloc_page(gfp_mask, order))
return NULL;
- /*
- * Check the zones suitable for the gfp_mask contain at least one
- * valid zone. It's possible to have an empty zonelist as a result
- * of __GFP_THISNODE and a memoryless node
- */
- if (unlikely(!zonelist->_zonerefs->zone))
- return NULL;
-
if (IS_ENABLED(CONFIG_CMA) && ac.migratetype == MIGRATE_MOVABLE)
alloc_flags |= ALLOC_CMA;
--
2.6.4
--
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next prev parent reply other threads:[~2016-04-12 10:13 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-12 10:12 [PATCH 00/24] Optimise page alloc/free fast paths v2 Mel Gorman
2016-04-12 10:12 ` [PATCH 01/24] mm, page_alloc: Only check PageCompound for high-order pages Mel Gorman
2016-04-12 10:12 ` [PATCH 02/24] mm, page_alloc: Use new PageAnonHead helper in the free page fast path Mel Gorman
2016-04-12 10:12 ` [PATCH 03/24] mm, page_alloc: Reduce branches in zone_statistics Mel Gorman
2016-04-12 10:12 ` [PATCH 04/24] mm, page_alloc: Inline zone_statistics Mel Gorman
2016-04-12 10:12 ` [PATCH 05/24] mm, page_alloc: Inline the fast path of the zonelist iterator Mel Gorman
2016-04-12 10:12 ` [PATCH 06/24] mm, page_alloc: Use __dec_zone_state for order-0 page allocation Mel Gorman
2016-04-12 10:12 ` [PATCH 07/24] mm, page_alloc: Avoid unnecessary zone lookups during pageblock operations Mel Gorman
2016-04-12 10:12 ` [PATCH 08/24] mm, page_alloc: Convert alloc_flags to unsigned Mel Gorman
2016-04-12 10:12 ` [PATCH 09/24] mm, page_alloc: Convert nr_fair_skipped to bool Mel Gorman
2016-04-12 10:12 ` [PATCH 10/24] mm, page_alloc: Remove unnecessary local variable in get_page_from_freelist Mel Gorman
2016-04-12 10:12 ` [PATCH 11/24] mm, page_alloc: Remove unnecessary initialisation " Mel Gorman
2016-04-12 10:12 ` [PATCH 12/24] mm, page_alloc: Remove unnecessary initialisation from __alloc_pages_nodemask() Mel Gorman
2016-04-12 10:12 ` Mel Gorman [this message]
2016-04-12 10:12 ` [PATCH 14/24] mm, page_alloc: Simplify last cpupid reset Mel Gorman
2016-04-12 10:12 ` [PATCH 15/24] mm, page_alloc: Move might_sleep_if check to the allocator slowpath Mel Gorman
2016-04-12 10:12 ` [PATCH 16/24] mm, page_alloc: Move __GFP_HARDWALL modifications out of the fastpath Mel Gorman
2016-04-12 10:12 ` [PATCH 17/24] mm, page_alloc: Reduce cost of fair zone allocation policy retry Mel Gorman
2016-04-12 10:12 ` [PATCH 18/24] mm, page_alloc: Shortcut watermark checks for order-0 pages Mel Gorman
2016-04-12 10:12 ` [PATCH 19/24] mm, page_alloc: Avoid looking up the first zone in a zonelist twice Mel Gorman
2016-04-12 10:12 ` [PATCH 20/24] mm, page_alloc: Check multiple page fields with a single branch Mel Gorman
2016-04-12 10:12 ` [PATCH 21/24] cpuset: use static key better and convert to new API Mel Gorman
2016-04-12 10:12 ` [PATCH 22/24] mm, page_alloc: Check once if a zone has isolated pageblocks Mel Gorman
2016-04-12 10:12 ` [PATCH 23/24] mm, page_alloc: Remove unnecessary variable from free_pcppages_bulk Mel Gorman
2016-04-12 10:12 ` [PATCH 24/24] mm, page_alloc: Do not lookup pcp migratetype during bulk free Mel Gorman
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