Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754526Ab3GAPeQ (ORCPT ); Mon, 1 Jul 2013 11:34:16 -0400 Received: from relay3-d.mail.gandi.net ([217.70.183.195]:39862 "EHLO relay3-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754341Ab3GAPeP (ORCPT ); Mon, 1 Jul 2013 11:34:15 -0400 X-Originating-IP: 50.43.39.152 Date: Mon, 1 Jul 2013 08:33:59 -0700 From: Josh Triplett To: "Paul E. McKenney" Cc: linux-kernel@vger.kernel.org, mingo@elte.hu, laijs@cn.fujitsu.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@polymtl.ca, niv@us.ibm.com, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, darren@dvhart.com, fweisbec@gmail.com, sbw@mit.edu Subject: Re: [PATCH RFC nohz_full v2 3/7] nohz_full: Add per-CPU idle-state tracking Message-ID: <20130701153359.GC2923@leaf> References: <20130628200949.GA17458@linux.vnet.ibm.com> <1372450222-19420-1-git-send-email-paulmck@linux.vnet.ibm.com> <1372450222-19420-3-git-send-email-paulmck@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1372450222-19420-3-git-send-email-paulmck@linux.vnet.ibm.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1284 Lines: 30 On Fri, Jun 28, 2013 at 01:10:18PM -0700, Paul E. McKenney wrote: > From: "Paul E. McKenney" > > This commit adds the code that updates the rcu_dyntick structure's > new fields to track the per-CPU idle state based on interrupts and > transitions into and out of the idle loop (NMIs are ignored because NMI > handlers cannot cleanly read out the time anyway). This code is similar > to the code that maintains RCU's idea of per-CPU idleness, but differs > in that RCU treats CPUs running in user mode as idle, where this new > code does not. [...] > --- a/kernel/rcutree_plugin.h > +++ b/kernel/rcutree_plugin.h > @@ -2380,6 +2380,76 @@ static void rcu_kick_nohz_cpu(int cpu) > #ifdef CONFIG_NO_HZ_FULL_SYSIDLE > > /* > + * Invoked to note exit from irq or task transition to idle. Note that > + * usermode execution does -not- count as idle here! The caller must > + * have disabled interrupts. Can you explain in the comments why this code doesn't treat userspace as idle/quiesced? - Josh Triplett -- 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/