From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757922Ab0DGNPd (ORCPT ); Wed, 7 Apr 2010 09:15:33 -0400 Received: from casper.infradead.org ([85.118.1.10]:50116 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757580Ab0DGNPb (ORCPT ); Wed, 7 Apr 2010 09:15:31 -0400 Subject: Re: [PATCH] perf_events: add PERF_SAMPLE_BRANCH_STACK From: Peter Zijlstra To: eranian@google.com Cc: linux-kernel@vger.kernel.org, mingo@elte.hu, paulus@samba.org, davem@davemloft.net, fweisbec@gmail.com, robert.richter@amd.com, perfmon2-devel@lists.sf.net, eranian@gmail.com In-Reply-To: <4bbc7fcf.100db80a.6b9f.fffffb14@mx.google.com> References: <4bbc7fcf.100db80a.6b9f.fffffb14@mx.google.com> Content-Type: text/plain; charset="UTF-8" Date: Wed, 07 Apr 2010 15:15:27 +0200 Message-ID: <1270646127.20295.976.camel@laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.28.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2010-04-07 at 14:45 +0200, Stephane Eranian wrote: > LBR is configured by default to record ALL taken branches. On some > processors, it is possible to filter the type of branches. This will > be supported in a subsequent patch. > > On other processors, the sample type is allowed but will generate a > sample where nr=0 as is the case with other sampling types. Right, so I already posted a patch like that: http://lkml.org/lkml/2010/3/4/160 and the reason its not merged is because there is no perf use-case for it. Ingo wants to avoid merging ABI bits for which there is no userspace around. We already have a few such things and we find that its too easy to regress on those part. So if you want this, please also implement a useful use-case in perf.