From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754337AbYAIFV6 (ORCPT ); Wed, 9 Jan 2008 00:21:58 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750937AbYAIFVt (ORCPT ); Wed, 9 Jan 2008 00:21:49 -0500 Received: from smtp-out02.alice-dsl.net ([88.44.60.12]:14396 "EHLO smtp-out02.alice-dsl.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750718AbYAIFVs (ORCPT ); Wed, 9 Jan 2008 00:21:48 -0500 Date: Wed, 9 Jan 2008 06:21:44 +0100 From: Andi Kleen To: Andi Kleen Cc: mingo@elte.hu, tglx@linutronix.de, linux-kernel@vger.kernel.org Subject: Re: More breakage in native_rdtsc out of line in git-x86 II Message-ID: <20080109052144.GA21032@basil.nowhere.org> References: <20080109035534.GA30321@basil.nowhere.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080109035534.GA30321@basil.nowhere.org> User-Agent: Mutt/1.5.13 (2006-08-11) X-OriginalArrivalTime: 09 Jan 2008 05:15:35.0697 (UTC) FILETIME=[AA52D010:01C8527E] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > I think the problem is that the vsyscall/vdso code calls it through > vread and for that it has to be exported. There seems to be also > another bug with the old style vsyscalls not using the TSC vread > that masks it on older glibc > > Stepping with gdb through old style vgettimeofday() confirms that RDTSC is > not used. > > A long time ago we had a similar problem once and it was because of a > problem exporting the vsyscall variables in vmlinux.lds.S -- looks like that > has reappeared. > > I think the new glibc shows it because it uses the vDSO not > the older vsyscall and the new vDSO probably still works. Anyways haven't > investigated why that is in detail yet, but that's a separate > regression. Actually that seems to be because the test system using the older glibc didn't use the TSC because it was marked unstable due a unsynchronized TSC. It should not have been -- this is a Core2 dual core single socket. Will investigate later what happened there. -Andi