tracing/perf: Reimplement TP_perf_assign() logic

The next patch tries to avoid the costly perf_trace_buf_* calls
when possible but there is a problem. We can only do this if
__task == NULL, perf_tp_event(task != NULL) has the additional
code for this case.

Unfortunately, TP_perf_assign/__perf_xxx which changes the default
values of __count/__task variables for perf_trace_buf_submit() is
called "too late", after we already did perf_trace_buf_prepare(),
and the optimization above can't work.

So this patch simply embeds __perf_xxx() into TP_ARGS(), this way
DECLARE_EVENT_CLASS() can use the result of assignments hidden in
"args" right after ftrace_get_offsets_##call() which is mostly
trivial. This allows us to have the fast-path "__task != NULL"
check at the start, see the next patch.

Link: http://lkml.kernel.org/r/20130806160844.GA2739@redhat.com

Tested-by: David Ahern <dsahern@gmail.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

2 files changed, 14 insertions, 21 deletions

diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h
index 249c024e67ae..2e7d9947a10d 100644
--- 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(__perf_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(__perf_task(tsk), __perf_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]",
@@ -376,7 +369,7 @@ DECLARE_EVENT_CLASS(sched_stat_runtime,
 
         TP_PROTO(struct task_struct *tsk, u64 runtime, u64 vruntime),
 
-        TP_ARGS(tsk, runtime, vruntime),
+        TP_ARGS(tsk, __perf_count(runtime), vruntime),
 
         TP_STRUCT__entry(
                 __array( char,  comm,   TASK_COMM_LEN   )
@@ -390,9 +383,6 @@ DECLARE_EVENT_CLASS(sched_stat_runtime,
                 __entry->pid            = tsk->pid;
                 __entry->runtime        = runtime;
                 __entry->vruntime       = vruntime;
-        )
-        TP_perf_assign(
-                __perf_count(runtime);
         ),
 
         TP_printk("comm=%s pid=%d runtime=%Lu [ns] vruntime=%Lu [ns]",
diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h
index 618af05f0be6..4163d93ccf38 100644
--- a/include/trace/ftrace.h
+++ b/include/trace/ftrace.h
@@ -507,8 +507,14 @@ static inline notrace int ftrace_get_offsets_##call(			\
 #undef TP_fast_assign
 #define TP_fast_assign(args...) args
 
-#undef TP_perf_assign
-#define TP_perf_assign(args...)
+#undef __perf_addr
+#define __perf_addr(a)  (a)
+
+#undef __perf_count
+#define __perf_count(c) (c)
+
+#undef __perf_task
+#define __perf_task(t)  (t)
 
 #undef DECLARE_EVENT_CLASS
 #define DECLARE_EVENT_CLASS(call, proto, args, tstruct, assign, print)  \
@@ -636,16 +642,13 @@ __attribute__((section("_ftrace_events"))) *__event_##call = &event_##call
 #define __get_str(field) (char *)__get_dynamic_array(field)
 
 #undef __perf_addr
-#define __perf_addr(a) __addr = (a)
+#define __perf_addr(a)  (__addr = (a))
 
 #undef __perf_count
-#define __perf_count(c) __count = (c)
+#define __perf_count(c) (__count = (c))
 
 #undef __perf_task
-#define __perf_task(t) __task = (t)
-
-#undef TP_perf_assign
-#define TP_perf_assign(args...) args
+#define __perf_task(t)  (__task = (t))
 
 #undef DECLARE_EVENT_CLASS
 #define DECLARE_EVENT_CLASS(call, proto, args, tstruct, assign, print)  \