[084/163] mm: kmem: switch to static_branch_likely() in memcg_kmem_enabled()

Commit Message

Andrew Morton Aug. 7, 2020, 6:21 a.m. UTC

From: Roman Gushchin <[e-mail]>
Subject: mm: kmem: switch to static_branch_likely() in memcg_kmem_enabled()

Currently memcg_kmem_enabled() is optimized for the kernel memory
accounting being off.  It was so for a long time, and arguably the reason
behind was that the kernel memory accounting was initially an opt-in
feature.  However, now it's on by default on both cgroup v1 and cgroup v2,
and it's on for all cgroups.  So let's switch over to
static_branch_likely() to reflect this fact.

Unlikely there is a significant performance difference, as the cost of a
memory allocation and its accounting significantly exceeds the cost of a
jump.  However, the conversion makes the code look more logically.

Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Roman Gushchin <[e-mail]>
Reviewed-by: Shakeel Butt <[e-mail]>
Acked-by: Vlastimil Babka <[e-mail]>
Cc: Johannes Weiner <[e-mail]>
Cc: Michal Hocko <[e-mail]>
Cc: Christoph Lameter <[e-mail]>
Cc: David Rientjes <[e-mail]>
Cc: Joonsoo Kim <[e-mail]>
Cc: Pekka Enberg <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
---

 include/linux/memcontrol.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Patch

--- a/include/linux/memcontrol.h~mm-kmem-switch-to-static_branch_likely-in-memcg_kmem_enabled
+++ a/include/linux/memcontrol.h
@@ -1448,7 +1448,7 @@  void memcg_put_cache_ids(void);
 
 static inline bool memcg_kmem_enabled(void)
 {
-	return static_branch_unlikely(&memcg_kmem_enabled_key);
+	return static_branch_likely(&memcg_kmem_enabled_key);
 }
 
 static inline bool memcg_kmem_bypass(void)