From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S274237AbUKBGiH (ORCPT ); Tue, 2 Nov 2004 01:38:07 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S265391AbUKBGiF (ORCPT ); Tue, 2 Nov 2004 01:38:05 -0500 Received: from zcars04f.nortelnetworks.com ([47.129.242.57]:52981 "EHLO zcars04f.nortelnetworks.com") by vger.kernel.org with ESMTP id S783090AbUKBGh7 (ORCPT ); Tue, 2 Nov 2004 01:37:59 -0500 Message-ID: <41872B2E.6020902@nortelnetworks.com> Date: Tue, 02 Nov 2004 00:37:34 -0600 X-Sybari-Space: 00000000 00000000 00000000 00000000 From: Chris Friesen User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.6) Gecko/20040113 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Linus Torvalds CC: linux-os@analogic.com, dean gaudet , Andreas Steinmetz , Kernel Mailing List , Richard Henderson , Andi Kleen , Andrew Morton , Jan Hubicka Subject: Re: Semaphore assembly-code bug References: <417550FB.8020404@drdos.com> <1098218286.8675.82.camel@mentorng.gurulabs.com> <41757478.4090402@drdos.com> <20041020034524.GD10638@michonline.com> <1098245904.23628.84.camel@krustophenia.net> <1098247307.23628.91.camel@krustophenia.net> <41826A7E.6020801@domdv.de> In-Reply-To: Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Linus Torvalds wrote: > On Intel, if I recall correctly, rdtsc is totally serializing, so you're > testing not just the instructions between the rdtsc's, but the length of > the pipeline, and the time it takes for stuff around it to calm down. Actually, the Intel docs say that rdtsc is not serializing (specifically for the P6 series, but linked off the P4 section of the site) and their sample performance measuring code for the P4 shows it using a serializing instruction before the call to rdtsc. Chris