From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2993096AbXCIJ76 (ORCPT ); Fri, 9 Mar 2007 04:59:58 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S637734AbXCIJ76 (ORCPT ); Fri, 9 Mar 2007 04:59:58 -0500 Received: from outbound-fra.frontbridge.com ([62.209.45.174]:22065 "EHLO outbound1-fra-R.bigfish.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2993095AbXCIJ74 (ORCPT ); Fri, 9 Mar 2007 04:59:56 -0500 X-BigFish: VP X-Server-Uuid: 5FC0E2DF-CD44-48CD-883A-0ED95B391E89 Date: Fri, 9 Mar 2007 10:57:10 +0100 From: "Joerg Roedel" To: "Andrew Morton" cc: discuss@x86-64.org, "Andi Kleen" , linux-kernel@vger.kernel.org Subject: Re: [PATCH 4/4] optimize and simplify get_cycles_sync() Message-ID: <20070309095710.GB8922@amd.com> References: <20070228140501.GA19452@amd.com> <20070228142554.GE19452@amd.com> <20070306162541.2b8a148d.akpm@linux-foundation.org> MIME-Version: 1.0 In-Reply-To: <20070306162541.2b8a148d.akpm@linux-foundation.org> User-Agent: mutt-ng/devel-r804 (Linux) X-OriginalArrivalTime: 09 Mar 2007 09:57:56.0851 (UTC) FILETIME=[69A24430:01C76231] X-WSS-ID: 69EFF04E328551529-01-01 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Mar 06, 2007 at 04:25:41PM -0800, Andrew Morton wrote: > On Wed, 28 Feb 2007 15:25:54 +0100 > "Joerg Roedel" wrote: > > > From: Joerg Roedel > > > > This patch simplifies the get_cycles_sync() function by removing the > > #ifdefs from it. Further it introduces an optimization for AMD > > processors. There the RDTSCP instruction is used instead of CPUID;RDTSC > > which is helpfull if the kernel runs as a KVM guest. Running as a guest > > makes CPUID very expensive because it causes an intercept of the guest. > > Problem: > > http://test.kernel.org/functional/index.html > > lots of builds fell over because their binutils versions don't understand > rdtscp. > > I don't know how recently rdtscp support was added to binutils, but > this is likely to be a problem. Perhaps we can change this patch to > embed the hex code for that opcode instead? Ok, I will submit an updated version soon. Thanks for pointing this out. Joerg -- Joerg Roedel Operating System Research Center AMD Saxony LLC & Co. KG