From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754330Ab3BDTBV (ORCPT ); Mon, 4 Feb 2013 14:01:21 -0500 Received: from e9.ny.us.ibm.com ([32.97.182.139]:52845 "EHLO e9.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750773Ab3BDTBU (ORCPT ); Mon, 4 Feb 2013 14:01:20 -0500 Date: Mon, 4 Feb 2013 10:59:38 -0800 From: "Paul E. McKenney" To: Steven Rostedt Cc: LKML , Ingo Molnar , Andrew Morton , Tetsuo Handa Subject: Re: [PATCH] rcu: Have rcu torture test select trace_clock Message-ID: <20130204185938.GY2632@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <1359993141.5642.61.camel@gandalf.local.home> <20130204165932.GW2632@linux.vnet.ibm.com> <1360002973.5642.66.camel@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1360002973.5642.66.camel@gandalf.local.home> User-Agent: Mutt/1.5.21 (2010-09-15) X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13020419-7182-0000-0000-000004ED4D6C Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Feb 04, 2013 at 01:36:13PM -0500, Steven Rostedt wrote: > On Mon, 2013-02-04 at 08:59 -0800, Paul E. McKenney wrote: > > On Mon, Feb 04, 2013 at 10:52:21AM -0500, Steven Rostedt wrote: > > > The rcu torture test uses trace_clock, and requires that it be built > > > into the kernel. If it is not, then we get the following build error: > > > > > > ERROR: "trace_clock_local" [kernel/rcutorture.ko] undefined! > > > > > > Reported-by: Tetsuo Handa > > > Signed-off-by: Steven Rostedt > > > > This would work, but would unnecessarily force trace_clock_local() > > to be defined when RCU tracing is disabled. So, would the alternative > > patch I posted work for you? > > > > Unfortunately the other patch wasn't Cc'd to LKML (I hate private > emails). > > I would suggest the following to be complete, why keep that extra divide > around? Good point, queued! Thanx, Paul > -- Steve > > I started with your patch: > > > rcu: Allow rcutorture to be built at low optimization levels > > The uses of trace_clock_local() are dead code when CONFIG_RCU_TRACE=n, > but some compilers might nevertheless generate code calling this function. > This commit therefore ensures that trace_clock_local() is invoked only > when CONFIG_RCU_TRACE=y. > > Reported-by: Tetsuo Handa > Signed-off-by: Paul E. McKenney > Signed-off-by: Steven Rostedt > > Index: linux-trace.git/kernel/rcutorture.c > =================================================================== > --- linux-trace.git.orig/kernel/rcutorture.c > +++ linux-trace.git/kernel/rcutorture.c > @@ -208,6 +208,20 @@ MODULE_PARM_DESC(rcutorture_runnable, "S > #define rcu_can_boost() 0 > #endif /* #else #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */ > > +#ifdef CONFIG_RCU_TRACE > +static u64 notrace rcu_trace_clock_local(void) > +{ > + u64 ts = trace_clock_local(); > + unsigned long __maybe_unused ts_rem = do_div(ts, NSEC_PER_USEC); > + return ts; > +} > +#else /* #ifdef CONFIG_RCU_TRACE */ > +static u64 notrace rcu_trace_clock_local(void) > +{ > + return 0ULL; > +} > +#endif /* #else #ifdef CONFIG_RCU_TRACE */ > + > static unsigned long shutdown_time; /* jiffies to system shutdown. */ > static unsigned long boost_starttime; /* jiffies of next boost test start. */ > DEFINE_MUTEX(boost_mutex); /* protect setting boost_starttime */ > @@ -1051,7 +1065,7 @@ static void rcu_torture_timer(unsigned l > > idx = cur_ops->readlock(); > completed = cur_ops->completed(); > - ts = trace_clock_local(); > + ts = rcu_trace_clock_local(); > p = rcu_dereference_check(rcu_torture_current, > rcu_read_lock_bh_held() || > rcu_read_lock_sched_held() || > @@ -1075,8 +1089,6 @@ static void rcu_torture_timer(unsigned l > } > completed_end = cur_ops->completed(); > if (pipe_count > 1) { > - unsigned long __maybe_unused ts_rem = do_div(ts, NSEC_PER_USEC); > - > do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu, ts, > completed, completed_end); > rcutorture_trace_dump(); > @@ -1122,7 +1134,7 @@ rcu_torture_reader(void *arg) > } > idx = cur_ops->readlock(); > completed = cur_ops->completed(); > - ts = trace_clock_local(); > + ts = rcu_trace_clock_local(); > p = rcu_dereference_check(rcu_torture_current, > rcu_read_lock_bh_held() || > rcu_read_lock_sched_held() || > @@ -1144,9 +1156,6 @@ rcu_torture_reader(void *arg) > } > completed_end = cur_ops->completed(); > if (pipe_count > 1) { > - unsigned long __maybe_unused ts_rem = > - do_div(ts, NSEC_PER_USEC); > - > do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu, > ts, completed, completed_end); > rcutorture_trace_dump(); > >