From mboxrd@z Thu Jan  1 00:00:00 1970
From: Frederic Weisbecker <fweisbec@gmail.com>
Date: Fri, 28 Jan 2011 17:54:14 +0000
Subject: Re: [PATCH 2/2] tracing, perf : add cpu hotplug trace events
Message-Id: <20110128175410.GB1761@nowhere>
List-Id: <linux-hotplug.vger.kernel.org>
References: <AANLkTi=hQpCVJWZ_Op4mhnehufcBg2=h_=q4xXD66tGb@mail.gmail.com>
 <20110126173241.GD1757@nowhere>
 <AANLkTikEvEyMZgmCozw_yt1enRJ2+GTvd02BY30hUJt0@mail.gmail.com>
In-Reply-To: <AANLkTikEvEyMZgmCozw_yt1enRJ2+GTvd02BY30hUJt0@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable
To: Vincent Guittot <vincent.guittot@linaro.org>
Cc: linux-kernel@vger.kernel.org, linux-hotplug@vger.kernel.org, rostedt@goodmis.org, amit.kucheria@linaro.org

On Thu, Jan 27, 2011 at 11:04:09AM +0100, Vincent Guittot wrote:
> On 26 January 2011 18:32, Frederic Weisbecker <fweisbec@gmail.com> wrote:
> > On Tue, Jan 25, 2011 at 09:54:59AM +0100, Vincent Guittot wrote:
> >> Please find below a new proposal for adding trace events for cpu hotpl=
ug.
> >> The goal is to measure the latency of each part (kernel, architecture)
> >> and also to trace the cpu hotplug activity with other power events. I
> >> have tested these traces events on an arm platform.
> >>
> >> Subject: [PATCH 1/2] add cpu hotplug tracepoints
> >>
> >> this patch adds new events for cpu hotplug tracing
> >> =A0* plug/unplug sequence
> >> =A0* core and architecture latency measurements
> >>
> >> Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
> >> ---
> >> =A0kernel/cpu.c | =A0 17 +++++++++++++++++
> >> =A01 files changed, 17 insertions(+), 0 deletions(-)
> >>
> >> diff --git a/kernel/cpu.c b/kernel/cpu.c
> >> index 156cc55..f04e9cf 100644
> >> --- a/kernel/cpu.c
> >> +++ b/kernel/cpu.c
> >> @@ -16,6 +16,9 @@
> >> =A0#include <linux/mutex.h>
> >> =A0#include <linux/gfp.h>
> >>
> >> +#define CREATE_TRACE_POINTS
> >> +#include <trace/events/cpu_hotplug.h>
> >> +
> >> =A0#ifdef CONFIG_SMP
> >> =A0/* Serializes the updates to cpu_online_mask, cpu_present_mask */
> >> =A0static DEFINE_MUTEX(cpu_add_remove_lock);
> >> @@ -200,7 +203,9 @@ static int __ref take_cpu_down(void *_param)
> >> =A0 =A0 =A0 int err;
> >>
> >> =A0 =A0 =A0 /* Ensure this CPU doesn't handle any more interrupts. */
> >> + =A0 =A0 trace_cpu_hotplug_arch_disable_start((unsigned int)(param->h=
cpu));
> >> =A0 =A0 =A0 err =3D __cpu_disable();
> >> + =A0 =A0 trace_cpu_hotplug_arch_disable_end((unsigned int)(param->hcp=
u));
> >
> > You should create a cpu var instead of doing that not very beautiful ca=
st
> > twice.
> >
>=20
> OK
>=20
> > Probably we should eventually rename arch_disable into just disable.
> >
> > And same for die, because otherwise the name is quite long.
> >
>=20
> If we remove the arch extension of these names, we will have
> trace_cpu_hotplug_arch_up for __cpu_up (trace_cpu_hotplug_up is
> already used) and trace_cpu_hotplug_disable for __cpu_disable. would
> that be acceptable ?

You're right.

Well, we could rename cpu_hotplug_arch_up into cpu_hotplug_enable,
but the overall result makes it confusing.

Let's keep it that way.