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>
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 437da0c..8a5bbe3 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -677,25 +677,14 @@
return (page->flags >> LAST_NID_PGSHIFT) & LAST_NID_MASK;
}
-static inline 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;
-}
+extern int page_xchg_last_nid(struct page *page, int nid);
static inline void reset_page_last_nid(struct page *page)
{
- page_xchg_last_nid(page, (1 << LAST_NID_SHIFT) - 1);
+ int nid = (1 << LAST_NID_SHIFT) - 1;
+
+ page->flags &= ~(LAST_NID_MASK << LAST_NID_PGSHIFT);
+ page->flags |= (nid & LAST_NID_MASK) << LAST_NID_PGSHIFT;
}
#endif /* LAST_NID_NOT_IN_PAGE_FLAGS */
#else
diff --git a/mm/mmzone.c b/mm/mmzone.c
index 4596d81..bce796e 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 @@
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