SLUB: Optimize slab_free() debug check
This patch optimizes slab_free() debug check to use "c->node != NUMA_NO_NODE"
instead of "c->node >= 0" because the former generates smaller code on x86-64:
Before:
4736: 48 39 70 08 cmp %rsi,0x8(%rax)
473a: 75 26 jne 4762 <kfree+0xa2>
473c: 44 8b 48 10 mov 0x10(%rax),%r9d
4740: 45 85 c9 test %r9d,%r9d
4743: 78 1d js 4762 <kfree+0xa2>
After:
4736: 48 39 70 08 cmp %rsi,0x8(%rax)
473a: 75 23 jne 475f <kfree+0x9f>
473c: 83 78 10 ff cmpl $0xffffffffffffffff,0x10(%rax)
4740: 74 1d je 475f <kfree+0x9f>
This patch also cleans up __slab_alloc() to use NUMA_NO_NODE instead of "-1"
for enabling debugging for a per-CPU cache.
Acked-by: Christoph Lameter <cl@linux.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
diff --git a/mm/slub.c b/mm/slub.c
index 9f121c1..a018019 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1718,7 +1718,7 @@
c->page->inuse++;
c->page->freelist = get_freepointer(s, object);
- c->node = -1;
+ c->node = NUMA_NO_NODE;
goto unlock_out;
}
@@ -1895,7 +1895,7 @@
slab_free_hook_irq(s, x);
- if (likely(page == c->page && c->node >= 0)) {
+ if (likely(page == c->page && c->node != NUMA_NO_NODE)) {
set_freepointer(s, object, c->freelist);
c->freelist = object;
stat(s, FREE_FASTPATH);