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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>
This commit is contained in:
Oleg Nesterov 2013-08-06 18:08:44 +02:00 committed by Steven Rostedt
parent 36009d07b7
commit 12473965c3
2 changed files with 14 additions and 21 deletions
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16
include/trace/events/sched.h
View File

@ -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]",

19
include/trace/ftrace.h
View File

@ -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) \