But that doesn't come free of cost, does it, seeing we've now pushed
the conditional inside kfree() itself. kfree() isn't inlined so we do
save on space but lose out on the extra time overhead for the common
case. Speaking of which ...
[PATCH] {slub, slob}: use unlikely() for kfree(ZERO_OR_NULL_PTR) check
Considering kfree(NULL) would normally occur only in error paths and
kfree(ZERO_SIZE_PTR) is uncommon as well, so let's use unlikely() for
the condition check in SLUB's and SLOB's kfree() to optimize for the
common case. SLAB has this already.
Signed-off-by: Satyam Sharma <satyam@infradead.org>
---
mm/slob.c | 2 +-
mm/slub.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/mm/slob.c b/mm/slob.c
index ec33fcd..37a8b9a 100644
--- a/mm/slob.c
+++ b/mm/slob.c
@@ -466,7 +466,7 @@ void kfree(const void *block)
{
struct slob_page *sp;
- if (ZERO_OR_NULL_PTR(block))
+ if (unlikely(ZERO_OR_NULL_PTR(block)))
return;
sp = (struct slob_page *)virt_to_page(block);
diff --git a/mm/slub.c b/mm/slub.c
index 69d02e3..3788537 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2467,7 +2467,7 @@ void kfree(const void *x)
* this comparison would be true for all "negative" pointers
* (which would cover the whole upper half of the address space).
*/
- if (ZERO_OR_NULL_PTR(x))
+ if (unlikely(ZERO_OR_NULL_PTR(x)))
return;
page = virt_to_head_page(x);
-
