Messages in this thread Patch in this message | | | Subject | Re: [PATCH] tracing: Add task activate/deactivate tracepoints | From | Peter Zijlstra <> | Date | Mon, 31 May 2010 18:18:35 +0200 |
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On Mon, 2010-05-31 at 16:48 +0200, Frederic Weisbecker wrote: > > Should we maybe cure this and rely on sched_switch() to detect sleeps? > > It seems natural since only the current task can go to sleep, its just > > that the whole preempt state gets a bit iffy.
How about something like the below?
Steve, is that proper usage of CREATE_TRACE_POINT?
--- Subject: sched, trace: Fix sched_switch() prev_state argument From: Peter Zijlstra <a.p.zijlstra@chello.nl> Date: Mon May 31 18:13:25 CEST 2010
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> --- include/trace/events/sched.h | 19 ++++++++++++++++++- 1 file changed, 18 insertions(+), 1 deletion(-)
Index: linux-2.6/include/trace/events/sched.h =================================================================== --- linux-2.6.orig/include/trace/events/sched.h +++ linux-2.6/include/trace/events/sched.h @@ -115,6 +115,23 @@ DEFINE_EVENT(sched_wakeup_template, sche 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;
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