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authorSteven Rostedt <rostedt@goodmis.org>2017-02-22 15:44:47 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2017-02-22 16:41:29 -0800
commite57b9d8c5ad08ed8cbca7e51fe252719a2845394 (patch)
treeb5f3c3e738323dd397355a4d173bd90315a6d53d /mm
parent870667553af5e18b2f3402c03f8c4f82381f0ec7 (diff)
mm/mmzone.c: swap likely to unlikely as code logic is different for next_zones_zonelist()
Commit 682a3385e773 ("mm, page_alloc: inline the fast path of the zonelist iterator") changed how next_zones_zonelist() is called, by adding a static inline function to do the fast path. This function adds: if (likely(!nodes && zonelist_zone_idx(z) <= highest_zoneidx)) return z; return __next_zones_zonelist(z, highest_zoneidx, nodes); Where __next_zones_zonelist() is only called when nodes is not NULL or zonelist_zone_idx(z) is less than highest_zoneidx. The original next_zone_zonelist() was converted to __next_zones_zonelist() but it still maintained: if (likely(nodes == NULL)) Which is now actually a very unlikely, as it is only called with nodes equal to NULL when zonelist_zone_idx(z) is greater than highest_zoneidx. Before this commit, this if had this statistic: correct incorrect % Function File Line ------- --------- - -------- ---- ---- 837895 446078 34 next_zones_zonelist mmzone.c 63 After this commit, it has: correct incorrect % Function File Line ------- --------- - -------- ---- ---- 10 173840 99 __next_zones_zonelist mmzone.c 63 Thus, the if statement is now much more unlikely than it ever was as a likely. Link: http://lkml.kernel.org/r/20170105200102.77989567@gandalf.local.home Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Acked-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/mmzone.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/mmzone.c b/mm/mmzone.c
index 5652be858e5e..a51c0a67ea3d 100644
--- a/mm/mmzone.c
+++ b/mm/mmzone.c
@@ -60,7 +60,7 @@ struct zoneref *__next_zones_zonelist(struct zoneref *z,
* Find the next suitable zone to use for the allocation.
* Only filter based on nodemask if it's set
*/
- if (likely(nodes == NULL))
+ if (unlikely(nodes == NULL))
while (zonelist_zone_idx(z) > highest_zoneidx)
z++;
else