Messages in this thread | | | Subject | Re: [PATCH 0/3] tracing: more list_empty(perf_events) checks | From | Steven Rostedt <> | Date | Mon, 17 Jun 2013 17:27:53 -0400 |
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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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