From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Paul E. McKenney" Subject: Re: [PATCH RFC idle 2/3] arm: Avoid invoking RCU when CPU is idle Date: Fri, 3 Feb 2012 12:23:34 -0800 Message-ID: <20120203202334.GM2382@linux.vnet.ibm.com> References: <20120202190708.GE2518@linux.vnet.ibm.com> <87obtgc1xx.fsf@ti.com> <4F2B1307.5010207@gmail.com> <1328223819.5882.133.camel@gandalf.stny.rr.com> <20120202232736.GL2518@linux.vnet.ibm.com> <1328237131.5882.135.camel@gandalf.stny.rr.com> <20120203060458.GF2380@linux.vnet.ibm.com> <1328295309.5882.178.camel@gandalf.stny.rr.com> <20120203194005.GK2382@linux.vnet.ibm.com> <1328299375.5882.204.camel@gandalf.stny.rr.com> Reply-To: paulmck@linux.vnet.ibm.com Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <1328299375.5882.204.camel@gandalf.stny.rr.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-arm-kernel-bounces@lists.infradead.org Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane.org@lists.infradead.org To: Steven Rostedt Cc: Nicolas Pitre , mathieu.desnoyers@polymtl.ca, peterz@infradead.org, fweisbec@gmail.com, Nicolas Ferre , dhowells@redhat.com, Lennert Buytenhek , Kevin Hilman , Kukjin Kim , Russell King , eric.dumazet@gmail.com, "Paul E. McKenney" , Magnus Damm , Tony Lindgren , dipankar@in.ibm.com, darren@dvhart.com, mingo@elte.hu, Jean-Christophe Plagniol-Villard , Len Brown , Amit Kucheria , patches@linaro.org, Will Deacon , josh@joshtriplett.org, Sekhar Nori , niv@us.ibm.com, linux-samsung-soc@vger.kernel.org, Barry Song , tglx@linutronix.de, linux-omap@v List-Id: linux-omap@vger.kernel.org On Fri, Feb 03, 2012 at 03:02:55PM -0500, Steven Rostedt wrote: > On Fri, 2012-02-03 at 11:40 -0800, Paul E. McKenney wrote: > > > So the idea is that if you have a trace event that is to be used in idle, > > you use TRACE_EVENT_IDLE() rather than TRACE_EVENT() to declare that > > trace event? That would work for me, and might make for fewer changes > > for the architecture guys. Also, this should address the code-size > > concerns we discussed yesterday. > > > > So sounds good! > > > > Is a DEFINE_EVENT_IDLE() also needed? Or prehaps a > > DECLARE_EVENT_CLASS_IDLE()? My guess is "yes" for at least one of the > > two based on include/trace/events/power.h. > > I'll have to take a look. I may even find a better way to do this too. Better is always better. ;-) > > I will keep RCU_NONIDLE() for at least a little while (reworking comments > > to point out TRACE_EVENT_IDLE() and friends) in case there turn out to > > be non-tracepoint uses of RCU in the idle loop. > > OK, I'll take a crack at this next Monday. Sounds good! I plan to push my stack to -next later today, but will yank my cpuidle commit as soon as your approach is available. They do not conflict because the rcu_idle_enter()s nest. Thanx, Paul