On Mon, 2013-06-17 at 22:18 +0200, Oleg Nesterov wrote:
> On 06/17, Oleg Nesterov wrote:
> >
> > DECLARE_EVENT_CLASS()->perf_trace_##call() is not trivial because
> > of __perf_task()
>
> Perhaps we can do something like below?
Did this actually compile for you?
>
> Then we can
>
> 1. kill __perf_addr(), __perf_count(), __perf_task() and
> TP_perf_assign()
>
> 2. Add the fast path check
>
> if (builtin_constant(__task) && !__task &&
> hlist_empty(head)))
> return;
>
> into perf_trace_call() right after ftrace_get_offsets_call().
>
> Doesn't look very nice, it relies on the fact that
> ftrace_get_offsets_call(args) evaluates TP_perf_arg()'s hidden in
> TP_ARGS().
>
> OTOH, the whole point of include/trace/ is to create the code which
> nobody except the maintainers can understand. At least I certainly
> can't ;) So perhaps this is fine.
It's the land of the MAGIC MACROs. You must be a MACRO WIZARD to
understand. I don't understand it unless I put on my MACRO WIZARD HAT.
>
> Oleg.
>
> --- a/include/trace/events/sched.h
> +++ b/include/trace/events/sched.h
> @@ -57,7 +57,7 @@ DECLARE_EVENT_CLASS(sched_wakeup_template,
>
> TP_PROTO(struct task_struct *p, int success),
>
> - TP_ARGS(p, success),
> + TP_ARGS(TP_perf_arg(__task, p), success),
>
> TP_STRUCT__entry(
> __array( char, comm, TASK_COMM_LEN )
> @@ -73,9 +73,6 @@ DECLARE_EVENT_CLASS(sched_wakeup_template,
> __entry->prio = p->prio;
> __entry->success = success;
> __entry->target_cpu = task_cpu(p);
> - )
> - TP_perf_assign(
> - __perf_task(p);
> ),
>
> TP_printk("comm=%s pid=%d prio=%d success=%d target_cpu=%03d",
> @@ -313,7 +310,7 @@ DECLARE_EVENT_CLASS(sched_stat_template,
>
> TP_PROTO(struct task_struct *tsk, u64 delay),
>
> - TP_ARGS(tsk, delay),
> + TP_ARGS(TP_perf_arg(__task, tsk), TP_perf_arg(__count, delay)),
>
> TP_STRUCT__entry(
> __array( char, comm, TASK_COMM_LEN )
> @@ -325,10 +322,6 @@ DECLARE_EVENT_CLASS(sched_stat_template,
> memcpy(__entry->comm, tsk->comm, TASK_COMM_LEN);
> __entry->pid = tsk->pid;
> __entry->delay = delay;
> - )
> - TP_perf_assign(
> - __perf_count(delay);
> - __perf_task(tsk);
> ),
>
> TP_printk("comm=%s pid=%d delay=%Lu [ns]",
> --- a/include/trace/ftrace.h
> +++ b/include/trace/ftrace.h
> @@ -506,6 +506,9 @@ static inline notrace int ftrace_get_offsets_##call(
> \
> #undef TP_perf_assign
> #define TP_perf_assign(args...)
>
> +#undef TP_perf_arg
> +#define TP_perf_arg(var, val) (val)
> +
> #undef DECLARE_EVENT_CLASS
> #define DECLARE_EVENT_CLASS(call, proto, args, tstruct, assign, print)
> \
> \
> @@ -643,6 +646,9 @@ __attribute__((section("_ftrace_events")))
> *__event_##call = &event_##call
> #undef TP_perf_assign
> #define TP_perf_assign(args...) args
>
> +#undef TP_perf_arg
> +#define TP_perf_arg(var, val) (var = (val))
> +
> #undef DECLARE_EVENT_CLASS
> #define DECLARE_EVENT_CLASS(call, proto, args, tstruct, assign, print)
> \
> static notrace void \
> @@ -659,13 +665,12 @@ perf_trace_##call(void *__data, proto)
> \
> int __data_size; \
> int rctx; \
> \
> - perf_fetch_caller_regs(&__regs); \
> - \
> __data_size = ftrace_get_offsets_##call(&__data_offsets, args); \
OK, so here the task gets assigned the val, and so does count.
This may not be a bad approach, but instead of having TP_perf_arg() in
events/sched.h, keep the TP_perf_task() and TP_perf_count(), and have
whatever is put there assigned. As "__task" and "__count" are hardcoded
into the macro. The you would have:
#undef TP_perf_task
#define TP_perf_task(val) (__task = (val))
#undef TP_perf_count
#define TP_perf_count(val) (__count = (val))
And that should work as well.
-- Steve
> __entry_size = ALIGN(__data_size + sizeof(*entry) + sizeof(u32),\
> sizeof(u64)); \
> __entry_size -= sizeof(u32); \
> \
> + perf_fetch_caller_regs(&__regs); \
> entry = (struct ftrace_raw_##call *)perf_trace_buf_prepare( \
> __entry_size, event_call->event.type, &__regs, &rctx); \
> if (!entry) \
--
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