From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751563AbWDYLsc (ORCPT ); Tue, 25 Apr 2006 07:48:32 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751543AbWDYLsc (ORCPT ); Tue, 25 Apr 2006 07:48:32 -0400 Received: from e32.co.us.ibm.com ([32.97.110.150]:10654 "EHLO e32.co.us.ibm.com") by vger.kernel.org with ESMTP id S1751515AbWDYLsb (ORCPT ); Tue, 25 Apr 2006 07:48:31 -0400 Date: Tue, 25 Apr 2006 04:48:54 -0700 From: "Paul E. McKenney" To: Martin Schwidefsky Cc: Andrew Morton , Heiko Carstens , dipankar@in.ibm.com, manfred@colorfullife.com, linux-kernel@vger.kernel.org, davem@davemloft.net Subject: Re: [patch] RCU: introduce rcu_soon_pending() interface Message-ID: <20060425114854.GB16719@us.ibm.com> Reply-To: paulmck@us.ibm.com References: <20060424111141.GC16007@osiris.boeblingen.de.ibm.com> <20060424160943.4bbdb788.akpm@osdl.org> <20060425112310.GA16612@us.ibm.com> <1145964817.5282.66.camel@localhost> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1145964817.5282.66.camel@localhost> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Apr 25, 2006 at 01:33:37PM +0200, Martin Schwidefsky wrote: > On Tue, 2006-04-25 at 04:23 -0700, Paul E. McKenney wrote: > > > Neither rcu_pending() nor rcu_soon_pending() are commented or documented. > > > Pity the poor user trying to work out what they do, and how they differ. > > > They're global symbols and they form part of the RCU API - they should be > > > kernel docified, please. > > > > Please note that the rcu_pending() interface was never intended for > > external use -- it is purely internal to the RCU infrastructure. > > If there is a new external use for rcu_pending(), then it would need to > > be documented. But I would rather this one stay internal -- different > > RCU implementations might need different things. > > > > So, what are we trying to do here? > > We are trying to find out if an idle cpu needs to continue to tick every > HZ or if we can put it into deep sleep. If there is any kind of rcu work > pending that requires the idle cpu to call in later via a timer > interrupt, we need to know. OK, this confirms my guess that you are acting as part of the RCU implementation rather than as a normal user of the RCU API. Thanx, Paul