From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754137AbYIEM1e (ORCPT ); Fri, 5 Sep 2008 08:27:34 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752714AbYIEM1Z (ORCPT ); Fri, 5 Sep 2008 08:27:25 -0400 Received: from vpn.id2.novell.com ([195.33.99.129]:29880 "EHLO vpn.id2.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752267AbYIEM1Y convert rfc822-to-8bit (ORCPT ); Fri, 5 Sep 2008 08:27:24 -0400 Message-Id: <48C141E1.76E4.0078.0@novell.com> X-Mailer: Novell GroupWise Internet Agent 8.0.0 Beta Date: Fri, 05 Sep 2008 13:27:45 +0100 From: "Jan Beulich" To: , , "Andrew Morton" , Cc: "Nick Piggin" , Subject: [PATCH 3/3] x86: ticket spin locks: reduce instruction dependencies Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8BIT Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Reduce the amount of partial register accesses in the NR_CPUS < 256 case, and slightly weaken resource dependencies in the other case. Signed-off-by: Jan Beulich Cc: Nick Piggin --- include/asm-x86/spinlock.h | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) --- linux-x86.orig/include/asm-x86/spinlock.h +++ linux-x86/include/asm-x86/spinlock.h @@ -21,8 +21,10 @@ #ifdef CONFIG_X86_32 # define LOCK_PTR_REG "a" +# define REG_PTR_MODE "k" #else # define LOCK_PTR_REG "D" +# define REG_PTR_MODE "q" #endif #if defined(CONFIG_X86_32) && \ @@ -77,19 +79,17 @@ static __always_inline void __ticket_spi static __always_inline int __ticket_spin_trylock(raw_spinlock_t *lock) { - int tmp; - short new; + int tmp, new; - asm volatile("movw %2,%w0\n\t" + asm volatile("movzwl %2, %0\n\t" "cmpb %h0,%b0\n\t" + "leal 0x100(%" REG_PTR_MODE "0), %1\n\t" "jne 1f\n\t" - "movw %w0,%w1\n\t" - "incb %h1\n\t" LOCK_PREFIX "cmpxchgw %w1,%2\n\t" "1:" "sete %b1\n\t" "movzbl %b1,%0\n\t" - : "=&a" (tmp), "=&Q" (new), "+m" (lock->slock) + : "=&a" (tmp), "=&q" (new), "+m" (lock->slock) : : "memory", "cc"); @@ -136,8 +136,8 @@ static __always_inline int __ticket_spin "movl %0,%1\n\t" "roll $16, %0\n\t" "cmpl %0,%1\n\t" + "leal 0x00010000(%" REG_PTR_MODE "0), %1\n\t" "jne 1f\n\t" - "addl $0x00010000, %1\n\t" LOCK_PREFIX "cmpxchgl %1,%2\n\t" "1:" "sete %b1\n\t"