SLUB: Optimize slab_free() debug check
authorPekka Enberg <penberg@kernel.org>
Sat, 2 Oct 2010 08:32:32 +0000 (11:32 +0300)
committerPekka Enberg <penberg@kernel.org>
Wed, 6 Oct 2010 13:52:26 +0000 (16:52 +0300)
commit15b7c5142049e7efc3071280e1370dc3b8add6f5
treec294e0aa90b52088e63c8c67d0963a973d304690
parent5d1f57e4d3d547b113ebd62f569be13bf485e53b
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>
mm/slub.c