linux-kernel - [PATCH v3 06/11] mm/page_alloc: when handling percpu_pagelist

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Message-Id: <1365618219-17154-7-git-send-email-cody@linux.vnet.ibm.com>
Date:	Wed, 10 Apr 2013 11:23:34 -0700
From:	Cody P Schafer <cody@...ux.vnet.ibm.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Gilad Ben-Yossef <gilad@...yossef.com>,
	Simon Jeons <simon.jeons@...il.com>,
	KOSAKI Motohiro <kosaki.motohiro@...il.com>,
	Mel Gorman <mgorman@...e.de>, Linux MM <linux-mm@...ck.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Cody P Schafer <cody@...ux.vnet.ibm.com>
Subject: [PATCH v3 06/11] mm/page_alloc: when handling percpu_pagelist_fraction, don't unneedly recalulate high

Simply moves calculation of the new 'high' value outside the
for_each_possible_cpu() loop, as it does not depend on the cpu.

Signed-off-by: Cody P Schafer <cody@...ux.vnet.ibm.com>
---
 mm/page_alloc.c | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 5c54a08..3447a4b 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5509,7 +5509,6 @@ int lowmem_reserve_ratio_sysctl_handler(ctl_table *table, int write,
  * cpu.  It is the fraction of total pages in each zone that a hot per cpu pagelist
  * can have before it gets flushed back to buddy allocator.
  */
-
 int percpu_pagelist_fraction_sysctl_handler(ctl_table *table, int write,
 	void __user *buffer, size_t *length, loff_t *ppos)
 {
@@ -5523,12 +5522,11 @@ int percpu_pagelist_fraction_sysctl_handler(ctl_table *table, int write,
 
 	mutex_lock(&pcp_batch_high_lock);
 	for_each_populated_zone(zone) {
-		for_each_possible_cpu(cpu) {
-			unsigned long  high;
-			high = zone->managed_pages / percpu_pagelist_fraction;
+		unsigned long  high;
+		high = zone->managed_pages / percpu_pagelist_fraction;
+		for_each_possible_cpu(cpu)
 			setup_pagelist_highmark(
-				per_cpu_ptr(zone->pageset, cpu), high);
-		}
+					per_cpu_ptr(zone->pageset, cpu), high);
 	}
 	mutex_unlock(&pcp_batch_high_lock);
 	return 0;
-- 
1.8.2.1

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