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sched, trace: Fix sched_switch() prev_state argument

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For CONFIG_PREEMPT=y kernels the sched_switch(.prev_state) argument isn't
useful because we can get preempted with current->state != TASK_RUNNING
without actually getting removed from the runqueue.

Cure this by treating all preempted tasks as runnable from the tracer's
point of view.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cautiously-acked-by: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1275322715.27810.23323.camel@twins>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Peter Zijlstra 2010-05-31 18:13:25 +02:00 committed by Ingo Molnar
parent e51fd5e22e
commit 02f726949f
1 changed files with 18 additions and 1 deletions
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19
include/trace/events/sched.h
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@ -115,6 +115,23 @@ DEFINE_EVENT(sched_wakeup_template, sched_wakeup_new,
TP_PROTO(struct task_struct *p, int success),
TP_ARGS(p, success));
#ifdef CREATE_TRACE_POINTS
static inline long __trace_sched_switch_state(struct task_struct *p)
{
long state = p->state;
#ifdef CONFIG_PREEMPT
/*
* For all intents and purposes a preempted task is a running task.
*/
if (task_thread_info(p)->preempt_count & PREEMPT_ACTIVE)
state = TASK_RUNNING;
#endif
return state;
}
#endif
/*
* Tracepoint for task switches, performed by the scheduler:
*/
@ -139,7 +156,7 @@ TRACE_EVENT(sched_switch,
memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN);
__entry->prev_pid = prev->pid;
__entry->prev_prio = prev->prio;
__entry->prev_state = prev->state;
__entry->prev_state = __trace_sched_switch_state(prev);
memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN);
__entry->next_pid = next->pid;
__entry->next_prio = next->prio;