On Sat, 5 Sep 2020 14:04:12 +0800
Muchun Song <songmuc...@bytedance.com> wrote:
> Introduce tracepoints for tasklets just like softirq does. In this case,
> we can calculate tasklet latency and know what tasklet run.
>
> Signed-off-by: Muchun Song <songmuc...@bytedance.com>
> ---
> include/trace/events/irq.h | 44 ++++++++++++++++++++++++++++++++++++++
> kernel/softirq.c | 2 ++
> 2 files changed, 46 insertions(+)
>
> diff --git a/include/trace/events/irq.h b/include/trace/events/irq.h
> index eeceafaaea4c..69a16f3a21c2 100644
> --- a/include/trace/events/irq.h
> +++ b/include/trace/events/irq.h
> @@ -160,6 +160,50 @@ DEFINE_EVENT(softirq, softirq_raise,
> TP_ARGS(vec_nr)
> );
>
> +DECLARE_EVENT_CLASS(tasklet,
> +
> + TP_PROTO(struct tasklet_struct *t),
> +
> + TP_ARGS(t),
> +
> + TP_STRUCT__entry(
> + __field( void *, callback )
> + ),
> +
> + TP_fast_assign(
> + __entry->callback = t->callback;
I think you need to replicate the logic in the code:
if (t->use_callback)
__entry->callback = t->callback;
else
__entry->callback = t->func;
-- Steve
> + ),
> +
> + TP_printk("callback=%ps", __entry->callback)
> +);
> +
> +/**
> + * tasklet_entry - called immediately before the tasklet handler
> + * @t: pointer to struct tasklet_struct
> + *
> + * When used in combination with the tasklet_exit tracepoint
> + * we can determine the tasklet handler routine.
> + */
> +DEFINE_EVENT(tasklet, tasklet_entry,
> +
> + TP_PROTO(struct tasklet_struct *t),
> +
> + TP_ARGS(t)
> +);
> +
> +/**
> + * tasklet_exit - called immediately after the tasklet handler returns
> + * @t: pointer to struct tasklet_struct
> + *
> + * When used in combination with the tasklet_entry tracepoint
> + * we can determine the tasklet handler routine.
> + */
> +DEFINE_EVENT(tasklet, tasklet_exit,
> +
> + TP_PROTO(struct tasklet_struct *t),
> +
> + TP_ARGS(t)
> +);
> #endif /* _TRACE_IRQ_H */
>
> /* This part must be outside protection */
> diff --git a/kernel/softirq.c b/kernel/softirq.c
> index bf88d7f62433..0f9f5b2cc3d3 100644
> --- a/kernel/softirq.c
> +++ b/kernel/softirq.c
> @@ -553,10 +553,12 @@ static void tasklet_action_common(struct softirq_action
> *a,
> if (!test_and_clear_bit(TASKLET_STATE_SCHED,
> &t->state))
> BUG();
> + trace_tasklet_entry(t);
> if (t->use_callback)
> t->callback(t);
> else
> t->func(t->data);
> + trace_tasklet_exit(t);
> tasklet_unlock(t);
> continue;
> }
