Re: [PATCH] kthread: Add kthread_work tracepoints

[Steven Rostedt]

On Sat, 10 Oct 2020 11:03:22 -0700
Rob Clark <robdclark@xxxxxxxxx> wrote:

> /**
> + * sched_kthread_work_execute_start - called immediately before the work callback
> + * @work:	pointer to struct kthread_work
> + *
> + * Allows to track kthread work execution.
> + */
> +TRACE_EVENT(sched_kthread_work_execute_start,
> +
> +	TP_PROTO(struct kthread_work *work),
> +
> +	TP_ARGS(work),
> +
> +	TP_STRUCT__entry(
> +		__field( void *,	work	)
> +		__field( void *,	function)
> +	),
> +
> +	TP_fast_assign(
> +		__entry->work		= work;
> +		__entry->function	= work->func;
> +	),
> +
> +	TP_printk("work struct %p: function %ps", __entry->work, __entry->function)
> +);
> +
> +/**
> + * sched_kthread_work_execute_end - called immediately after the work callback
> + * @work:	pointer to struct work_struct
> + * @function:   pointer to worker function
> + *
> + * Allows to track workqueue execution.
> + */
> +TRACE_EVENT(sched_kthread_work_execute_end,
> +
> +	TP_PROTO(struct kthread_work *work, kthread_work_func_t function),
> +
> +	TP_ARGS(work, function),
> +
> +	TP_STRUCT__entry(
> +		__field( void *,	work	)
> +		__field( void *,	function)
> +	),
> +
> +	TP_fast_assign(
> +		__entry->work		= work;
> +		__entry->function	= function;
> +	),
> +
> +	TP_printk("work struct %p: function %ps", __entry->work, __entry->function)
> +);
> +


Please combine the above into:

DECLARE_EVENT_CLASS(sched_kthread_work_execute_template,

	TP_PROTO(struct kthread_work *work),

	TP_ARGS(work),

	TP_STRUCT__entry(
		__field( void *,	work	)
		__field( void *,	function)
	),

	TP_fast_assign(
		__entry->work		= work;
		__entry->function	= work->func;
	),

	TP_printk("work struct %p: function %ps", __entry->work, __entry->function)
);

DEFINE_EVENT(sched_kthread_work_execute_template, sched_kthread_work_execute_start,
	TP_PROTO(struct kthread_work *work),
	TP_ARGS(work));

DEFINE_EVENT(sched_kthread_work_execute_template, sched_kthread_work_execute_end,
	TP_PROTO(struct kthread_work *work),
	TP_ARGS(work));

As events are cheap, classes are expensive (size wise), and a TRACE_EVENT()
is really just a CLASS and EVENT for a single instance.

-- Steve