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Message-ID: <20190919123559.2931e0ef@gandalf.local.home>
Date: Thu, 19 Sep 2019 12:35:59 -0400
From: Steven Rostedt <rostedt@...dmis.org>
To: Matthias Kaehlcke <mka@...omium.org>
Cc: MyungJoo Ham <myungjoo.ham@...sung.com>,
Kyungmin Park <kyungmin.park@...sung.com>,
Chanwoo Choi <cw00.choi@...sung.com>,
Ingo Molnar <mingo@...hat.com>, linux-pm@...r.kernel.org,
linux-kernel@...r.kernel.org,
Douglas Anderson <dianders@...omium.org>
Subject: Re: [PATCH] devfreq: Add tracepoint for frequency changes
On Wed, 18 Sep 2019 12:15:37 -0700
Matthias Kaehlcke <mka@...omium.org> wrote:
> Add a tracepoint for frequency changes of devfreq devices and
> use it.
>
> Signed-off-by: Matthias Kaehlcke <mka@...omium.org>
> ---
> drivers/devfreq/devfreq.c | 3 +++
> include/trace/events/devfreq.h | 18 ++++++++++++++++++
> 2 files changed, 21 insertions(+)
>
> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
> index ab22bf8a12d6..32de1f6ac776 100644
> --- a/drivers/devfreq/devfreq.c
> +++ b/drivers/devfreq/devfreq.c
> @@ -317,6 +317,9 @@ static int devfreq_set_target(struct devfreq *devfreq, unsigned long new_freq,
>
> devfreq->previous_freq = new_freq;
>
> + if (new_freq != cur_freq)
I would make this:
if (trace_devfreq_frequency_enabled() && new_freq != cur_freq)
Because this would place the second check into the "nop" portion of the
code, keeping the test from being performed if the devfreq_frequency
trace point is not enabled. Slight micro optimization, but still enough
to add it.
-- Steve
> + trace_devfreq_frequency(devfreq, new_freq);
> +
> if (devfreq->suspend_freq)
> devfreq->resume_freq = cur_freq;
>
> diff --git a/include/trace/events/devfreq.h b/include/trace/events/devfreq.h
> index cf5b8772175d..a62d32fe3c33 100644
> --- a/include/trace/events/devfreq.h
> +++ b/include/trace/events/devfreq.h
> @@ -8,6 +8,24 @@
> #include <linux/devfreq.h>
> #include <linux/tracepoint.h>
>
> +TRACE_EVENT(devfreq_frequency,
> + TP_PROTO(struct devfreq *devfreq, unsigned long freq),
> +
> + TP_ARGS(devfreq, freq),
> +
> + TP_STRUCT__entry(
> + __string(dev_name, dev_name(&devfreq->dev))
> + __field(unsigned long, freq)
> + ),
> +
> + TP_fast_assign(
> + __assign_str(dev_name, dev_name(&devfreq->dev));
> + __entry->freq = freq;
> + ),
> +
> + TP_printk("dev_name=%s freq=%lu", __get_str(dev_name), __entry->freq)
> +);
> +
> TRACE_EVENT(devfreq_monitor,
> TP_PROTO(struct devfreq *devfreq),
>
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