commit afb9b0a68eb667e9b9da7f582a8e6d078970157d
author Arun Bharadwaj <abharadw@codeaurora.org> Wed Jul 03 10:35:02 2013 -0700
committer Ruchi Kandoi <kandoiruchi@google.com> Mon Nov 30 23:46:16 2015 +0000
tree d64b90f258a3706444caab841e9ed8d868cbd18c
parent db1dc42c7de051b1a845e09b63e82b3e5e60d481

tracing/sched: Add trace events to track cpu hotplug.

Add ftrace event trace_sched_cpu_hotplug to track cpu
hot-add and hot-remove events.

This is useful in a variety of power, performance and
debug analysis scenarios.

Change-Id: I5d202c7a229ffacc3aafb7cf9afee0b0ee7b0931
Signed-off-by: Arun Bharadwaj <abharadw@codeaurora.org>

include/trace/events/sched.h

diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h
index af7480b..4e82758 100644
--- a/include/trace/events/sched.h
+++ b/include/trace/events/sched.h
@@ -179,6 +179,31 @@
 		  __entry->orig_cpu, __entry->dest_cpu)
 );
 
+/*
+ * Tracepoint for a CPU going offline/online:
+ */
+TRACE_EVENT(sched_cpu_hotplug,
+
+	TP_PROTO(int affected_cpu, int error, int status),
+
+	TP_ARGS(affected_cpu, error, status),
+
+	TP_STRUCT__entry(
+		__field(	int,	affected_cpu		)
+		__field(	int,	error			)
+		__field(	int,	status			)
+	),
+
+	TP_fast_assign(
+		__entry->affected_cpu	= affected_cpu;
+		__entry->error		= error;
+		__entry->status		= status;
+	),
+
+	TP_printk("cpu %d %s error=%d", __entry->affected_cpu,
+		__entry->status ? "online" : "offline", __entry->error)
+);
+
 DECLARE_EVENT_CLASS(sched_process_template,
 
 	TP_PROTO(struct task_struct *p),

kernel/cpu.c

diff --git a/kernel/cpu.c b/kernel/cpu.c
index 2fb146b..f85feb6 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -22,6 +22,8 @@
 #include <linux/lockdep.h>
 #include <trace/events/power.h>
 
+#include <trace/events/sched.h>
+
 #include "smpboot.h"
 
 #ifdef CONFIG_SMP
@@ -424,6 +426,7 @@
 
 out_release:
 	cpu_hotplug_done();
+	trace_sched_cpu_hotplug(cpu, err, 0);
 	if (!err)
 		cpu_notify_nofail(CPU_POST_DEAD | mod, hcpu);
 	return err;
@@ -499,6 +502,7 @@
 		__cpu_notify(CPU_UP_CANCELED | mod, hcpu, nr_calls, NULL);
 out:
 	cpu_hotplug_done();
+	trace_sched_cpu_hotplug(cpu, ret, 1);
 
 	return ret;
 }