From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753194Ab0JBIkd (ORCPT ); Sat, 2 Oct 2010 04:40:33 -0400 Received: from filtteri6.pp.htv.fi ([213.243.153.189]:43852 "EHLO filtteri6.pp.htv.fi" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752936Ab0JBIkc (ORCPT ); Sat, 2 Oct 2010 04:40:32 -0400 From: Pekka Enberg To: linux-kernel@vger.kernel.org Cc: Pekka Enberg , Christoph Lameter , David Rientjes Subject: [RFC/PATCH] SLUB: Optimize slab_free() debug check Date: Sat, 2 Oct 2010 11:40:25 +0300 Message-Id: <1286008825-5567-1-git-send-email-penberg@kernel.org> X-Mailer: git-send-email 1.6.3.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 473c: 44 8b 48 10 mov 0x10(%rax),%r9d 4740: 45 85 c9 test %r9d,%r9d 4743: 78 1d js 4762 After: 4736: 48 39 70 08 cmp %rsi,0x8(%rax) 473a: 75 23 jne 475f 473c: 83 78 10 ff cmpl $0xffffffffffffffff,0x10(%rax) 4740: 74 1d je 475f This patch also cleans up __slab_alloc() to use NUMA_NO_NODE instead of "-1" for enabling debugging for a per-CPU cache. Cc: Christoph Lameter Cc: David Rientjes Signed-off-by: Pekka Enberg --- mm/slub.c | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-) 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 @@ debug: 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 @@ static __always_inline void slab_free(struct kmem_cache *s, 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); -- 1.6.3.3