From bc4ba393c007248f76c05945abb7b7b892cdd1cc Mon Sep 17 00:00:00 2001
From: Christoph Lameter <clameter@sgi.com>
Date: Wed, 6 Dec 2006 20:33:02 -0800
Subject: [PATCH] drain_node_page(): Drain pages in batch units

drain_node_pages() currently drains the complete pageset of all pages.  If
there are a large number of pages in the queues then we may hold off
interrupts for too long.

Duplicate the method used in free_hot_cold_page.  Only drain pcp->batch
pages at one time.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index a840e70..86f2984 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -685,9 +685,15 @@ void drain_node_pages(int nodeid)
 
 			pcp = &pset->pcp[i];
 			if (pcp->count) {
+				int to_drain;
+
 				local_irq_save(flags);
-				free_pages_bulk(zone, pcp->count, &pcp->list, 0);
-				pcp->count = 0;
+				if (pcp->count >= pcp->batch)
+					to_drain = pcp->batch;
+				else
+					to_drain = pcp->count;
+				free_pages_bulk(zone, to_drain, &pcp->list, 0);
+				pcp->count -= to_drain;
 				local_irq_restore(flags);
 			}
 		}
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