From: Keir Fraser <keir.fraser@citrix.com>
Date: Wed, 16 Dec 2009 16:43:33 +0000 (+0000)
Subject: xen/balloon: prefer using pages from balloon in alloc_empty_pages_and_pagevec()
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=1b3e8c9b66849f723243f6e89a8c583271054fa4;p=legacy%2Flinux-2.6.18-xen.git

xen/balloon: prefer using pages from balloon in alloc_empty_pages_and_pagevec()

This is both faster and less demanding on kernel resources.

Likely also something that could be done in the pv-ops tree (though it
would need some adjustment to deal with the balloon_order!=0 case).

Signed-off-by: Jan Beulich <jbeulich@novell.com>
---

diff --git a/drivers/xen/balloon/balloon.c b/drivers/xen/balloon/balloon.c
index 0bb27345..cf1878c7 100644
--- a/drivers/xen/balloon/balloon.c
+++ b/drivers/xen/balloon/balloon.c
@@ -602,6 +602,17 @@ struct page **alloc_empty_pages_and_pagevec(int nr_pages)
 		return NULL;
 
 	for (i = 0; i < nr_pages; i++) {
+		balloon_lock(flags);
+		page = balloon_first_page();
+		if (page && !PageHighMem(page)) {
+			UNLIST_PAGE(page);
+			bs.balloon_low--;
+			balloon_unlock(flags);
+			pagevec[i] = page;
+			continue;
+		}
+		balloon_unlock(flags);
+
 		page = pagevec[i] = alloc_page(GFP_KERNEL|__GFP_COLD);
 		if (page == NULL)
 			goto err;