lkml.org 
[lkml]   [2010]   [May]   [31]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
SubjectRe: [PATCH] tracing: Add task activate/deactivate tracepoints
From
Date
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;


\
 
 \ /
  Last update: 2010-05-31 18:21    [from the cache]
©2003-2014 Jasper Spaans. Advertise on this site