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[PATCH 4/4] sched: add trace event for idle injection

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  [PATCH 4/4] sched: add trace event for idle injection Jacob Pan <jacob.jun.pan@linux.intel.com> - 2015-11-13 21:00 +0100
    Re: [PATCH 4/4] sched: add trace event for idle injection kbuild test robot <lkp@intel.com> - 2015-11-13 21:20 +0100

#1269184 — [PATCH 4/4] sched: add trace event for idle injection

Trace events for idle injection can be used to determine
timer activities for checking synchronization. In addition they
also helps to determine when the runqueue is throttled.

Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
---
 include/linux/sched.h        |  5 +++++
 include/trace/events/sched.h | 25 +++++++++++++++++++++++++
 kernel/sched/fair.c          |  3 +++
 3 files changed, 33 insertions(+)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index ff551a3..99c79bf 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -3189,6 +3189,11 @@ extern int proc_sched_cfs_idle_inject_duration_handler(struct ctl_table *table,
 						int write,
 						void __user *buffer,
 						size_t *length, loff_t *ppos);
+enum cfs_idle_inject_action {
+	CFS_IDLE_INJECT_TIMER,    /* timer sync point */
+	CFS_IDLE_INJECT_FORCED,   /* idle forced in rq */
+	CFS_IDLE_INJECT_YIELD_SOFTIRQ   /* yield to pending softirq */
+};
 #endif
 
 #endif
diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h
index 539d6bc..52c11c1 100644
--- a/include/trace/events/sched.h
+++ b/include/trace/events/sched.h
@@ -566,6 +566,31 @@ TRACE_EVENT(sched_wake_idle_without_ipi,
 
 	TP_printk("cpu=%d", __entry->cpu)
 );
+
+#ifdef CONFIG_CFS_IDLE_INJECT
+/*
+ * Tracepoint for idle injection
+ */
+TRACE_EVENT(sched_cfs_idle_inject,
+
+	TP_PROTO(enum cfs_idle_inject_action action, int throttled),
+
+	TP_ARGS(action, throttled),
+
+	TP_STRUCT__entry(
+		__field(enum cfs_idle_inject_action, action)
+		__field(int, throttled)
+	),
+
+	TP_fast_assign(
+		__entry->action = action;
+		__entry->throttled = throttled;
+	),
+
+	TP_printk("action:%d throttled:%d", __entry->action, __entry->throttled)
+);
+#endif
+
 #endif /* _TRACE_SCHED_H */
 
 /* This part must be outside protection */
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index a0cd777..20027eb 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5248,8 +5248,10 @@ idle:
 	if (in_forced_idle(cfs_rq)) {
 		if (unlikely(local_softirq_pending())) {
 			__unthrottle_cfs_rq(cfs_rq);
+			trace_sched_cfs_idle_inject(CFS_IDLE_INJECT_YIELD_SOFTIRQ, 1);
 			goto again;
 		}
+		trace_sched_cfs_idle_inject(CFS_IDLE_INJECT_FORCED, 1);
 		return NULL;
 	}
 	/*
@@ -8432,6 +8434,7 @@ static enum hrtimer_restart idle_inject_timer_fn(struct hrtimer *hrtimer)
 		throttle_rq(cpu);
 	}
 	raw_cpu_write(idle_injected, !status);
+	trace_sched_cfs_idle_inject(CFS_IDLE_INJECT_TIMER, !status);
 
 	return HRTIMER_RESTART;
 }
-- 
1.9.1

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#1269191

[Multipart message — attachments visible in raw view] — view raw

Hi Jacob,

[auto build test ERROR on: tip/sched/core]
[also build test ERROR on: v4.3 next-20151113]

url:    https://github.com/0day-ci/linux/commits/Jacob-Pan/CFS-idle-injection/20151114-035732
config: cris-etrax-100lx_v2_defconfig (attached as .config)
reproduce:
        wget https://git.kernel.org/cgit/linux/kernel/git/wfg/lkp-tests.git/plain/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        make.cross ARCH=cris 

All errors (new ones prefixed by >>):

   kernel/sched/fair.c: In function 'pick_next_task_fair':
>> kernel/sched/fair.c:5316:4: error: implicit declaration of function 'trace_sched_cfs_idle_inject' [-Werror=implicit-function-declaration]
>> kernel/sched/fair.c:5316:32: error: 'CFS_IDLE_INJECT_YIELD_SOFTIRQ' undeclared (first use in this function)
   kernel/sched/fair.c:5316:32: note: each undeclared identifier is reported only once for each function it appears in
>> kernel/sched/fair.c:5319:31: error: 'CFS_IDLE_INJECT_FORCED' undeclared (first use in this function)
   cc1: some warnings being treated as errors

vim +/trace_sched_cfs_idle_inject +5316 kernel/sched/fair.c

  5310		return p;
  5311	
  5312	idle:
  5313		if (in_forced_idle(cfs_rq)) {
  5314			if (unlikely(local_softirq_pending())) {
  5315				__unthrottle_cfs_rq(cfs_rq);
> 5316				trace_sched_cfs_idle_inject(CFS_IDLE_INJECT_YIELD_SOFTIRQ, 1);
  5317				goto again;
  5318			}
> 5319			trace_sched_cfs_idle_inject(CFS_IDLE_INJECT_FORCED, 1);
  5320			return NULL;
  5321		}
  5322		/*

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

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