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authorMel Gorman <mgorman@suse.de>2013-02-22 16:34:46 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2013-02-23 17:50:18 -0800
commit4468b8f1e2d32ce79ef4bcb8e00d7e88627f1c3a (patch)
treea73555b462198c396da08acab928a788f3733b71 /mm/mmzone.c
parent6acc8b02517d7063b25490b26215834bd2f363c8 (diff)
downloadlinux-4468b8f1e2d32ce79ef4bcb8e00d7e88627f1c3a.tar.bz2
mm: uninline page_xchg_last_nid()
Andrew Morton pointed out that page_xchg_last_nid() and reset_page_last_nid() were "getting nuttily large" and asked that it be investigated. reset_page_last_nid() is on the page free path and it would be unfortunate to make that path more expensive than it needs to be. Due to the internal use of page_xchg_last_nid() it is already too expensive but fortunately, it should also be impossible for the page->flags to be updated in parallel when we call reset_page_last_nid(). Instead of unlining the function, it uses a simplier implementation that assumes no parallel updates and should now be sufficiently short for inlining. page_xchg_last_nid() is called in paths that are already quite expensive (splitting huge page, fault handling, migration) and it is reasonable to uninline. There was not really a good place to place the function but mm/mmzone.c was the closest fit IMO. This patch saved 128 bytes of text in the vmlinux file for the kernel configuration I used for testing automatic NUMA balancing. Signed-off-by: Mel Gorman <mgorman@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/mmzone.c')
-rw-r--r--mm/mmzone.c20
1 files changed, 19 insertions, 1 deletions
diff --git a/mm/mmzone.c b/mm/mmzone.c
index 4596d81b89b1..bce796e8487f 100644
--- a/mm/mmzone.c
+++ b/mm/mmzone.c
@@ -1,7 +1,7 @@
/*
* linux/mm/mmzone.c
*
- * management codes for pgdats and zones.
+ * management codes for pgdats, zones and page flags
*/
@@ -96,3 +96,21 @@ void lruvec_init(struct lruvec *lruvec)
for_each_lru(lru)
INIT_LIST_HEAD(&lruvec->lists[lru]);
}
+
+#if defined(CONFIG_NUMA_BALANCING) && !defined(LAST_NID_NOT_IN_PAGE_FLAGS)
+int page_xchg_last_nid(struct page *page, int nid)
+{
+ unsigned long old_flags, flags;
+ int last_nid;
+
+ do {
+ old_flags = flags = page->flags;
+ last_nid = page_last_nid(page);
+
+ flags &= ~(LAST_NID_MASK << LAST_NID_PGSHIFT);
+ flags |= (nid & LAST_NID_MASK) << LAST_NID_PGSHIFT;
+ } while (unlikely(cmpxchg(&page->flags, old_flags, flags) != old_flags));
+
+ return last_nid;
+}
+#endif