From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754684Ab0IJPrO (ORCPT ); Fri, 10 Sep 2010 11:47:14 -0400 Received: from casper.infradead.org ([85.118.1.10]:40193 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754540Ab0IJPrN convert rfc822-to-8bit (ORCPT ); Fri, 10 Sep 2010 11:47:13 -0400 Subject: Re: [tip:perf/core] perf: Per-pmu-per-cpu contexts From: Peter Zijlstra To: paulmck@linux.vnet.ibm.com Cc: Frederic Weisbecker , mingo@redhat.com, hpa@zytor.com, paulus@samba.org, linux-kernel@vger.kernel.org, eranian@googlemail.com, yanmin_zhang@linux.intel.com, robert.richter@amd.com, ming.m.lin@intel.com, tglx@linutronix.de, mingo@elte.hu, linux-tip-commits@vger.kernel.org In-Reply-To: <20100910153750.GC2400@linux.vnet.ibm.com> References: <20100910145426.GA5618@nowhere> <20100910153750.GC2400@linux.vnet.ibm.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT Date: Fri, 10 Sep 2010 17:46:34 +0200 Message-ID: <1284133594.402.94.camel@laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.28.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2010-09-10 at 08:37 -0700, Paul E. McKenney wrote: > > So, you say below that it works because synchronize_srcu(), that > > waits for qs after touching pmus, implies synchronize_sched(), right? > > Ook... My current plans to fold SRCU into TREE_RCU would invalidate > this assumption. > > Maybe we need some sort of primitive that concurrently waits for > multiple types of RCU grace periods? Nah, but I was thinking that any kind of preemptible rcu sync would imply a sched rcu sync. If not strictly implied I'd have no problem simply writing: synchronize_rcu_sched(); synchronize_srcu();