From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933046Ab1CXS0Z (ORCPT ); Thu, 24 Mar 2011 14:26:25 -0400 Received: from mail-fx0-f46.google.com ([209.85.161.46]:52588 "EHLO mail-fx0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756912Ab1CXS0Y (ORCPT ); Thu, 24 Mar 2011 14:26:24 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:user-agent:mime-version:to:cc:subject :references:in-reply-to:content-type:content-transfer-encoding; b=E1uPDmv9fwhxXI7cGwH0y1auYHL+J56dfacExxElFVtHVI9ueysQKPRhjIFYQNxYJV 6pgC5jjUVi2yL8An6vVPQk3bIePG4E+FoxBnv3nG87JLDrE6Qu4Dz6kEFU7YBhjeXjvE UzagU/oV4SwnEpJ2fQhg3FqlbQ7REir7NDadE= Message-ID: <4D8B8CC4.8000500@gmail.com> Date: Thu, 24 Mar 2011 21:26:12 +0300 From: Cyrill Gorcunov User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.14) Gecko/20110223 Thunderbird/3.1.8 MIME-Version: 1.0 To: Don Zickus CC: Ingo Molnar , Lin Ming , Linux kernel mailing list Subject: Re: [PATCH -tip] perf, x86: P4 PMU - Add missing read of a counter before test References: <20110324084819.GH30812@elte.hu> <4D8B6569.2030001@gmail.com> <20110324163332.GA2414@elte.hu> <4D8B7570.40101@gmail.com> <20110324182221.GF1239@redhat.com> In-Reply-To: <20110324182221.GF1239@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/24/2011 09:22 PM, Don Zickus wrote: > On Thu, Mar 24, 2011 at 07:46:40PM +0300, Cyrill Gorcunov wrote: >>>> The read of a proper MSR register was missed so instead of a counter the >>>> configration register is tested (it has ARCH_P4_UNFLAGGED_BIT always cleared) >>>> and unflagged overflows never have been catched. Fix it by reading a proper >>>> MSR register. >>> >>> So what effect does this have on the regular perf user? Please try to describe >>> the real-life effect of the bug/problem fixed here. >>> >>> Thanks, >>> >>> Ingo >> >> Unflagged overflows never have been catched due to missed read of a register which >> is to signalize about it, and as result unknown nmi may happen leading to >> "Dazen and confused" message. That is what supposed to be in changelog? > > I think Ingo is looking for something like this: > Thanks Don, if Ingo agree I can update it. -- Cyrill