Re: [PATCH 2/2] tracing, sched: Add a new tracepoint for sleeptime

[Steven Rostedt <rostedt@goodmis.org>]

On Tue, 2011-12-20 at 10:09 -0800, Arun Sharma wrote:
> If CONFIG_SCHEDSTATS is defined, the kernel maintains
> information about how long the task was sleeping or
> in the case of iowait, blocking in the kernel before
> getting woken up.
> 
> Note: this information is only provided for sched_fair.
> Other scheduling classes may choose to provide this in
> the future.
> 
> Note: the delay includes the time spent on the runqueue
> as well.
> 
> Signed-off-by: Arun Sharma <asharma@fb.com>
> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
> Cc: Steven Rostedt <rostedt@goodmis.org>
> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
> Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
> Cc: Andrew Vagin <avagin@openvz.org>
> Cc: Frederic Weisbecker <fweisbec@gmail.com>
> Cc: Ingo Molnar <mingo@elte.hu>
> Cc: linux-kernel@vger.kernel.org
> ---
>  include/trace/events/sched.h |   48 ++++++++++++++++++++++++++++++++++++++++++
>  kernel/sched/core.c          |    1 +
>  2 files changed, 49 insertions(+), 0 deletions(-)
> 
> diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h
> index 959ff18..5189220 100644
> --- a/include/trace/events/sched.h
> +++ b/include/trace/events/sched.h
> @@ -363,6 +363,54 @@ TRACE_EVENT(sched_stat_runtime,
>  			(unsigned long long)__entry->vruntime)
>  );
>  
> +#ifdef CREATE_TRACE_POINTS

Why the #ifdef? a static inline is fine to keep in the open. If nothing
uses it, then it just wont be used or defined.

-- Steve

> +static inline u64 trace_get_sleeptime(struct task_struct *tsk) 
> +{
> +#ifdef CONFIG_SCHEDSTATS
> +	u64 block, sleep;
> +
> +	block = tsk->se.statistics.block_start;
> +	sleep = tsk->se.statistics.sleep_start;
> +
> +	return block ? block : sleep ? sleep : 0;
> +#else
> +	return 0;
> +#endif
> +}
> +#endif
> +
> +