Messages in this thread | | | Subject | Re: [PATCH] tracing: Add task activate/deactivate tracepoints | From | Steven Rostedt <> | Date | Mon, 31 May 2010 12:37:33 -0400 |
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Expect slow responses from me today. It's a US Holiday.
On Mon, 2010-05-31 at 18:18 +0200, Peter Zijlstra wrote: > 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
I guess this could work. I can't think of anything that would cause this to fail. But this is not exactly what the CREATE_TRACE_POINTS macro was for.
Maybe we could make a CREATE_UTIL_FUNCTIONS macro that the define_trace.h can unset like it does with CREATE_TRACE_POINTS before recursively including the trace headers.
Maybe I'm a bit paranoid, but I'm a little nervous to extend the CREATE_TRACE_POINTS macro to be used within the header to create utility functions, although, currently I don't think there's anything technically wrong in doing so.
-- Steve
> +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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