Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756487AbZFKGgf (ORCPT ); Thu, 11 Jun 2009 02:36:35 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752824AbZFKGg1 (ORCPT ); Thu, 11 Jun 2009 02:36:27 -0400 Received: from casper.infradead.org ([85.118.1.10]:45729 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752324AbZFKGg1 (ORCPT ); Thu, 11 Jun 2009 02:36:27 -0400 Subject: RE: [tip:tracing/core] Revert "x86, bts: reenable ptrace branch trace support" From: Peter Zijlstra To: "Metzger, Markus T" Cc: "linux-kernel@vger.kernel.org" , "mingo@redhat.com" , "hpa@zytor.com" , "oleg@redhat.com" , "tglx@linutronix.de" , "mingo@elte.hu" , "linux-tip-commits@vger.kernel.org" In-Reply-To: <928CFBE8E7CB0040959E56B4EA41A77EBBC6544B@irsmsx504.ger.corp.intel.com> References: <928CFBE8E7CB0040959E56B4EA41A77EBBC6544B@irsmsx504.ger.corp.intel.com> Content-Type: text/plain Date: Thu, 11 Jun 2009 08:36:23 +0200 Message-Id: <1244702183.6691.8.camel@laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.26.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2190 Lines: 48 On Thu, 2009-06-11 at 07:30 +0100, Metzger, Markus T wrote: > >-----Original Message----- > >From: tip-bot for Ingo Molnar [mailto:mingo@elte.hu] > >Sent: Thursday, June 11, 2009 1:37 AM > >To: linux-tip-commits@vger.kernel.org > >Cc: hpa@zytor.com; mingo@redhat.com; peterz@infradead.org; Metzger, Markus T; oleg@redhat.com; > >tglx@linutronix.de; mingo@elte.hu > >Subject: [tip:tracing/core] Revert "x86, bts: reenable ptrace branch trace support" > > > >Commit-ID: 511b01bdf64ad8a38414096eab283c7784aebfc4 > >Gitweb: http://git.kernel.org/tip/511b01bdf64ad8a38414096eab283c7784aebfc4 > >Author: Ingo Molnar > >AuthorDate: Thu, 11 Jun 2009 00:32:00 +0200 > >Committer: Ingo Molnar > >CommitDate: Thu, 11 Jun 2009 00:32:00 +0200 > > > >Revert "x86, bts: reenable ptrace branch trace support" > > > >This reverts commit 7e0bfad24d85de7cf2202a7b0ce51de11a077b21. > > > >A late objection to the ABI has arrived: > > > > http://lkml.org/lkml/2009/6/10/253 > > I thought that this has been resolved. See for example http://lkml.org/lkml/2009/6/10/257. > > Peters concerns were that Debug Store details are exposed to user space, which is > not the case. Debug Store itself is fully in-kernel and the expectation of a > user-defined buffer can be implemented on top of the Debug Store changes that > Peter expects are needed to support PEBS. > > A user-defined trace buffer size is required to support different usage models. > Some users only need a small amount of trace, whereas others need a big amount. > The interface will have to reflect that in some way. Right, your last email did explain how we could keep per task in-kernel buffers and fill them from the DS and still have them of user-specified size. That would indeed keep the proposed ABI workable, what I'm still not liking is that this buffer is in-kernel, but I guess that might be something for other people to have an opinion on. -- 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/