linux-kernel - Re: [PATCH v2 1/2] trace: events: add devfreq trace event file

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Message-ID: <bfe5eced-712e-774a-a5d9-3649e276e848@samsung.com>
Date:   Mon, 18 Feb 2019 14:40:58 +0900
From:   Chanwoo Choi <cw00.choi@...sung.com>
To:     Lukasz Luba <l.luba@...tner.samsung.com>,
        linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org
Cc:     b.zolnierkie@...sung.com, myungjoo.ham@...sung.com,
        kyungmin.park@...sung.com, m.szyprowski@...sung.com,
        s.nawrocki@...sung.com, mka@...omium.org, rostedt@...dmis.org,
        mingo@...hat.com
Subject: Re: [PATCH v2 1/2] trace: events: add devfreq trace event file

Hi Lukasz,

On 19. 2. 15. 오후 10:05, Lukasz Luba wrote:
> The patch adds a new file for with trace events for devfreq
> framework. They are used for performance analysis of the framework.
> It also contains updates in MAINTAINERS file adding new entry for
> devfreq maintainers.
> 
> Signed-off-by: Lukasz Luba <l.luba@...tner.samsung.com>
> ---
>  MAINTAINERS                    |  1 +
>  include/trace/events/devfreq.h | 40 ++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 41 insertions(+)
>  create mode 100644 include/trace/events/devfreq.h
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 41ce5f4..9c44076 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -4447,6 +4447,7 @@ S:	Maintained
>  F:	drivers/devfreq/
>  F:	include/linux/devfreq.h
>  F:	Documentation/devicetree/bindings/devfreq/
> +F:	include/trace/events/devfreq.h
>  
>  DEVICE FREQUENCY EVENT (DEVFREQ-EVENT)
>  M:	Chanwoo Choi <cw00.choi@...sung.com>
> diff --git a/include/trace/events/devfreq.h b/include/trace/events/devfreq.h
> new file mode 100644
> index 0000000..ce83dba
> --- /dev/null
> +++ b/include/trace/events/devfreq.h
> @@ -0,0 +1,40 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#undef TRACE_SYSTEM
> +#define TRACE_SYSTEM devfreq
> +
> +#if !defined(_TRACE_DEVFREQ_H) || defined(TRACE_HEADER_MULTI_READ)
> +#define _TRACE_DEVFREQ_H
> +
> +#include <linux/devfreq.h>
> +#include <linux/tracepoint.h>
> +
> +TRACE_EVENT(devfreq_monitor,
> +	TP_PROTO(struct devfreq *devfreq),
> +
> +	TP_ARGS(devfreq),
> +
> +	TP_STRUCT__entry(
> +		__field(unsigned long, freq)
> +		__field(unsigned long, busy_time)
> +		__field(unsigned long, total_time)
> +		__field(unsigned int, polling_ms)
> +		__string(dev_name, dev_name(&devfreq->dev))
> +	),
> +
> +	TP_fast_assign(
> +		__entry->freq = devfreq->previous_freq;
> +		__entry->busy_time = devfreq->last_status.busy_time;
> +		__entry->total_time = devfreq->last_status.total_time;
> +		__entry->polling_ms = devfreq->profile->polling_ms;
> +		__assign_str(dev_name, dev_name(&devfreq->dev));
> +	),
> +
> +	TP_printk("dev_name=%s freq=%lu polling_ms=%u load=%lu",
> +		__get_str(dev_name), __entry->freq, __entry->polling_ms,
> +		__entry->total_time == 0 ? 100 :

I case of __entry->total_time is zero,
why do you show '100' instead of '0'(zero)?
I think that it might make the some confusion for user.

If it show the '100' in case of "__entry->total_time is zero",
it cannot distinguish between the real 100% utilization
and "total_time is zero".

> +			(100 * __entry->busy_time) / __entry->total_time)
> +);
> +#endif /* _TRACE_DEVFREQ_H */
> +
> +/* This part must be outside protection */
> +#include <trace/define_trace.h>
> 


-- 
Best Regards,
Chanwoo Choi
Samsung Electronics