From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758735Ab0EGWE5 (ORCPT ); Fri, 7 May 2010 18:04:57 -0400 Received: from mga05.intel.com ([192.55.52.89]:25708 "EHLO fmsmga101.fm.intel.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754095Ab0EGWE4 (ORCPT ); Fri, 7 May 2010 18:04:56 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.52,350,1270450800"; d="scan'208";a="565220322" From: Jacob Pan To: LKML , "H. Peter Anvin" , Ingo Molnar , Thomas Gleixner , Arjan van de Ven , Alek Du Cc: Jacob Pan Subject: [PATCH] x86: avoid check hlt for newer cpus Date: Fri, 7 May 2010 14:59:45 -0700 Message-Id: <1273269585-14346-1-git-send-email-jacob.jun.pan@linux.intel.com> 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 Check hlt instruction was targeted for some older CPUs. It is an expensive operation in that it takes 4 ticks to break out the check. We can avoid such check completely for newer x86 cpus ( family > 5). http://lkml.org/lkml/2010/5/7/395 Signed-off-by: Jacob Pan --- arch/x86/kernel/cpu/bugs.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index 01a2652..36d9bcf 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -86,7 +86,7 @@ static void __init check_fpu(void) static void __init check_hlt(void) { - if (paravirt_enabled()) + if (paravirt_enabled() || boot_cpu_data.x86 > 5) return; printk(KERN_INFO "Checking 'hlt' instruction... "); -- 1.6.3.3