From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756852Ab0EJLjJ (ORCPT ); Mon, 10 May 2010 07:39:09 -0400 Received: from ozlabs.org ([203.10.76.45]:35110 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756710Ab0EJLjH (ORCPT ); Mon, 10 May 2010 07:39:07 -0400 Date: Mon, 10 May 2010 21:38:57 +1000 From: Paul Mackerras To: Peter Zijlstra Cc: mingo@redhat.com, hpa@zytor.com, eranian@google.com, linux-kernel@vger.kernel.org, davem@davemloft.net, fweisbec@gmail.com, ming.m.lin@intel.com, tglx@linutronix.de, mingo@elte.hu, linux-tip-commits@vger.kernel.org Subject: Re: [tip:perf/core] perf: Add group scheduling transactional APIs Message-ID: <20100510113857.GA5131@brick.ozlabs.ibm.com> References: <1272002160.5707.60.camel@minggr.sh.intel.com> <1273269355.1642.383.camel@laptop> <20100508102841.GA10650@brick.ozlabs.ibm.com> <1273479115.5605.3329.camel@twins> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1273479115.5605.3329.camel@twins> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, May 10, 2010 at 10:11:55AM +0200, Peter Zijlstra wrote: > Can't you compute n_txn_start by subtracting n_added from n_events ? Well, n_added says how many have been added since hw_perf_disable, and we could get multiple transactions inside a hw_perf_disable/enable pair, if we're scheduling multiple groups on. So n_events - n_added doesn't tell us how many have been added in this transaction -- unless I'm mistaken and there is a one transaction per hw_perf_disable/enable rule, but I didn't see that written anywhere, and it does seem to be explicitly one transaction per group. Paul.