Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752281AbYKQPPL (ORCPT ); Mon, 17 Nov 2008 10:15:11 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751630AbYKQPO6 (ORCPT ); Mon, 17 Nov 2008 10:14:58 -0500 Received: from one.firstfloor.org ([213.235.205.2]:41241 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750783AbYKQPO5 (ORCPT ); Mon, 17 Nov 2008 10:14:57 -0500 Date: Mon, 17 Nov 2008 16:24:34 +0100 From: Andi Kleen To: eranian@gmail.com Cc: Andi Kleen , Eric Dumazet , Mikael Pettersson , Robert Richter , oprofile-list@lists.sf.net, Ingo Molnar , Jiri Kosina , Jiri Benc , Vilem Marsik , Pekka Enberg , linux-kernel@vger.kernel.org Subject: Re: Oprofile : need to adjust PC by 16 bytes Message-ID: <20081117152434.GM6703@one.firstfloor.org> References: <20081113213744.GA8429@elte.hu> <491CA0DC.8070405@cosmosbay.com> <491D987F.1000301@cosmosbay.com> <18717.44751.459961.277998@harpo.it.uu.se> <491DB391.2040701@cosmosbay.com> <20081114175056.GK3810@one.firstfloor.org> <491EF942.1090709@cosmosbay.com> <20081115183627.GL3810@one.firstfloor.org> <7c86c4470811170702y127c9249m9b86b65a38a3e05c@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <7c86c4470811170702y127c9249m9b86b65a38a3e05c@mail.gmail.com> User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 853 Lines: 28 On Mon, Nov 17, 2008 at 04:02:19PM +0100, stephane eranian wrote: Thanks for explaining it better than I could. Just a minor correction. > But it can be very large when overflow happens > during a kernel critical section > where interrupts are off. Actually oprofile uses the NMI to avoid that particular problem. It still has limits, e.g. no profiling of SMM sections. > There is nothing SW can do about all of this. Yes profiling on a out of order machine is hard. > Furthermore, PEBS can record samples while > in kernel critical sections. Again with oprofile that works too without PEBS. -Andi -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/