Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757878AbZFJMva (ORCPT ); Wed, 10 Jun 2009 08:51:30 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756528AbZFJMvW (ORCPT ); Wed, 10 Jun 2009 08:51:22 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:39060 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755967AbZFJMvW (ORCPT ); Wed, 10 Jun 2009 08:51:22 -0400 Date: Wed, 10 Jun 2009 14:51:08 +0200 From: Ingo Molnar To: Peter Zijlstra Cc: mingo@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org, markus.t.metzger@intel.com, tglx@linutronix.de, oleg@redhat.com, linux-tip-commits@vger.kernel.org Subject: Re: [tip:tracing/core] x86, bts: reenable ptrace branch trace support Message-ID: <20090610125108.GA13506@elte.hu> References: <20090424094448.A30216@sedona.ch.intel.com> <1244637843.13761.11786.camel@twins> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1244637843.13761.11786.camel@twins> User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.5 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1805 Lines: 46 * Peter Zijlstra wrote: > On Thu, 2009-05-07 at 09:25 +0000, tip-bot for Markus Metzger wrote: > > Commit-ID: 7e0bfad24d85de7cf2202a7b0ce51de11a077b21 > > Gitweb: http://git.kernel.org/tip/7e0bfad24d85de7cf2202a7b0ce51de11a077b21 > > Author: Markus Metzger > > AuthorDate: Fri, 24 Apr 2009 09:44:48 +0200 > > Committer: Ingo Molnar > > CommitDate: Fri, 24 Apr 2009 10:18:51 +0200 > > > > x86, bts: reenable ptrace branch trace support > > > > The races found by Oleg Nesterov have been fixed. > > > > Reenable branch trace support. > > > > Signed-off-by: Markus Metzger > > Acked-by: Oleg Nesterov > > LKML-Reference: <20090424094448.A30216@sedona.ch.intel.com> > > Signed-off-by: Ingo Molnar > > OK, this whole BTS thing worries me because it seems to expose too > much of the Intel Debug Store thingy to the outside world. > > The thing is, once we do PEBS from inside the kernel, we'll have > to share the debug store, and the way this thing sets it up isn't > really going to work. > > So what I'd like to see is having this debug store removed from > the interface and abstracted away as cpu resource -- a single page > when in use should suffice I think. > > If you want to expose a buffer to userspace, use the regular > mmap() interface and fill those pages from the DS interrupt > handler. hm, that makes sense indeed. We are in the merge window now - Markus, what's your suggestion? Ingo -- 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/