On Sat, Sep 19, 2020 at 12:46 AM Steven Rostedt wrote:
>
> On Sat, 5 Sep 2020 14:04:12 +0800
> Muchun Song 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
> > ---
> > 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;
The `callback` and `func` is union and `callback` will replace
`func` someday in the feature. So I think that here we use
`t->callback` is enough. Right? Thanks.
>
> -- 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;
> > }
>
--
Yours,
Muchun
