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>
diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h
index ea7a203..1c20181 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),
diff --git a/kernel/cpu.c b/kernel/cpu.c
index 975b1a5..2912551 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -17,6 +17,8 @@
#include <linux/gfp.h>
#include <linux/suspend.h>
+#include <trace/events/sched.h>
+
#ifdef CONFIG_SMP
/* Serializes the updates to cpu_online_mask, cpu_present_mask */
static DEFINE_MUTEX(cpu_add_remove_lock);
@@ -290,6 +292,7 @@
out_release:
cpu_hotplug_done();
+ trace_sched_cpu_hotplug(cpu, err, 0);
if (!err)
cpu_notify_nofail(CPU_POST_DEAD | mod, hcpu);
return err;
@@ -347,6 +350,7 @@
if (ret != 0)
__cpu_notify(CPU_UP_CANCELED | mod, hcpu, nr_calls, NULL);
cpu_hotplug_done();
+ trace_sched_cpu_hotplug(cpu, ret, 1);
return ret;
}