linux-kernel - Re: [PATCH v3 2/3] tracing, function_graph: add additional marks to signal very large function execution time

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Message-ID: <20141117081940.667ee391@gandalf.local.home>
Date:	Mon, 17 Nov 2014 08:19:40 -0500
From:	Steven Rostedt <rostedt@...dmis.org>
To:	byungchul.park@....com
Cc:	mingo@...hat.com, linux-kernel@...r.kernel.org,
	seungho1.park@....com, jolsa@...hat.com
Subject: Re: [PATCH v3 2/3] tracing, function_graph: add additional marks to
 signal very large function execution time

On Mon, 17 Nov 2014 09:41:57 +0900
byungchul.park@....com wrote:

> From: Byungchul Park <byungchul.park@....com>
> 
> diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
> index 385391f..d89868a 100644
> --- a/kernel/trace/trace.h
> +++ b/kernel/trace/trace.h
> @@ -331,6 +331,25 @@ struct tracer_flags {
>  /* Makes more easy to define a tracer opt */
>  #define TRACER_OPT(s, b)	.name = #s, .bit = b
>  
> +/* trace overhead mark */
> +struct trace_mark {
> +	unsigned long long	val; /* unit: nsec */
> +	char			sym;
> +};
> +
> +#define MARK(v, s) {.val = v, .sym = s}
> +
> +static inline char trace_duration_mark(unsigned long long d,
> +				       const struct trace_mark m[],
> +				       int size)
> +{
> +	int idx = size;
> +
> +	if (size <= 0) return ' ';
> +	while (d <= m[--idx].val && idx > 0);
> +
> +	return m[idx].sym;
> +}
>  
>  /**
>   * struct tracer - a specific tracer and its callbacks to interact with debugfs
> diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
> index cb33f46..d9ac09f 100644
> --- a/kernel/trace/trace_functions_graph.c
> +++ b/kernel/trace/trace_functions_graph.c
> @@ -797,6 +797,19 @@ trace_print_graph_duration(unsigned long long duration, struct trace_seq *s)
>  	return TRACE_TYPE_HANDLED;
>  }

Move the #define MARK() down to here (just before it is used). And add
a "#undef MARK" before it. You never know if some header file might
include a #define MARK somewhere.


>  
> +static const struct trace_mark mark[] = {
> +	MARK(0ULL		, ' '), /* 0 usecs */
> +	MARK(10000ULL		, '+'), /* 10 usecs */
> +	MARK(100000ULL		, '!'), /* 100 usecs */
> +	MARK(1000000ULL		, '#'), /* 1000 usecs */
> +	MARK(1000000000ULL	, '$'), /* 1 sec */
> +};

You can add a "#undef MARK" here too, just to let people know that you
are done with it. But this one is optional.

Thanks!

-- Steve


> +
> +static inline char find_trace_mark(unsigned long long d)
> +{
> +	return trace_duration_mark(d, mark, ARRAY_SIZE(mark));
> +}
> +

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