Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758966AbZGCScs (ORCPT ); Fri, 3 Jul 2009 14:32:48 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758941AbZGCSch (ORCPT ); Fri, 3 Jul 2009 14:32:37 -0400 Received: from hera.kernel.org ([140.211.167.34]:53639 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758948AbZGCScf (ORCPT ); Fri, 3 Jul 2009 14:32:35 -0400 Date: Fri, 3 Jul 2009 18:31:25 GMT From: tip-bot for Ingo Molnar To: linux-tip-commits@vger.kernel.org Cc: linux-kernel@vger.kernel.org, acme@redhat.com, paulus@samba.org, hpa@zytor.com, mingo@redhat.com, eric.dumazet@gmail.com, a.p.zijlstra@chello.nl, torvalds@linux-foundation.org, efault@gmx.de, arnd@arndb.de, dhowells@redhat.com, fweisbec@gmail.com, akpm@linux-foundation.org, tglx@linutronix.de, mingo@elte.hu Reply-To: mingo@redhat.com, hpa@zytor.com, paulus@samba.org, acme@redhat.com, linux-kernel@vger.kernel.org, eric.dumazet@gmail.com, torvalds@linux-foundation.org, a.p.zijlstra@chello.nl, efault@gmx.de, arnd@arndb.de, fweisbec@gmail.com, dhowells@redhat.com, akpm@linux-foundation.org, tglx@linutronix.de, mingo@elte.hu In-Reply-To: <20090703111033.6e9627de@infradead.org> References: <20090703111033.6e9627de@infradead.org> Subject: [tip:perfcounters/urgent] x86: atomic64: Optimize CMPXCHG8B sequences to not use the LOCK prefix Message-ID: Git-Commit-ID: 07aa81b2169a2cb5e62ad239fd8055ef484e4f79 X-Mailer: tip-git-log-daemon MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.0 (hera.kernel.org [127.0.0.1]); Fri, 03 Jul 2009 18:31:26 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2310 Lines: 65 Commit-ID: 07aa81b2169a2cb5e62ad239fd8055ef484e4f79 Gitweb: http://git.kernel.org/tip/07aa81b2169a2cb5e62ad239fd8055ef484e4f79 Author: Ingo Molnar AuthorDate: Fri, 3 Jul 2009 20:15:58 +0200 Committer: Ingo Molnar CommitDate: Fri, 3 Jul 2009 20:24:00 +0200 x86: atomic64: Optimize CMPXCHG8B sequences to not use the LOCK prefix Arjan noted that the CMPXCHG8B instruction has an implicit lock prefix, so there's no need to add the prefix explicitly. This gives us smaller code and smaller alternative-instructions tables. Cc: Linus Torvalds Cc: Eric Dumazet Cc: Peter Zijlstra Cc: Mike Galbraith Cc: Paul Mackerras Cc: Arnaldo Carvalho de Melo Cc: Frederic Weisbecker Cc: David Howells Cc: Andrew Morton Cc: Arnd Bergmann LKML-Reference: <20090703111033.6e9627de@infradead.org> Signed-off-by: Ingo Molnar --- arch/x86/include/asm/atomic_32.h | 2 +- arch/x86/lib/atomic64_32.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/include/asm/atomic_32.h b/arch/x86/include/asm/atomic_32.h index de89959..130f4ab 100644 --- a/arch/x86/include/asm/atomic_32.h +++ b/arch/x86/include/asm/atomic_32.h @@ -302,7 +302,7 @@ static inline u64 atomic64_read(atomic64_t *ptr) asm volatile( "mov %%ebx, %%eax\n\t" "mov %%ecx, %%edx\n\t" - LOCK_PREFIX "cmpxchg8b %1\n" + "cmpxchg8b %1\n" : "=&A" (res) : "m" (*ptr) ); diff --git a/arch/x86/lib/atomic64_32.c b/arch/x86/lib/atomic64_32.c index d79f4ac..e4a6671 100644 --- a/arch/x86/lib/atomic64_32.c +++ b/arch/x86/lib/atomic64_32.c @@ -12,7 +12,7 @@ static noinline u64 cmpxchg8b(u64 *ptr, u64 old, u64 new) u32 high = new >> 32; asm volatile( - LOCK_PREFIX "cmpxchg8b %1\n" + "cmpxchg8b %1\n" : "+A" (old), "+m" (*ptr) : "b" (low), "c" (high) ); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/