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Subject[PATCH V6 2/2] tracing, perf: add cpu hotplug trace events
From
Trace the cpu state and the time spent in core and arch code

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
---
kernel/cpu.c | 18 ++++++++++++++++++
1 files changed, 18 insertions(+), 0 deletions(-)

diff --git a/kernel/cpu.c b/kernel/cpu.c
index 156cc55..8abb84b 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -16,6 +16,9 @@
#include <linux/mutex.h>
#include <linux/gfp.h>

+#define CREATE_TRACE_POINTS
+#include <trace/events/cpu_hotplug.h>
+
#ifdef CONFIG_SMP
/* Serializes the updates to cpu_online_mask, cpu_present_mask */
static DEFINE_MUTEX(cpu_add_remove_lock);
@@ -197,10 +200,13 @@ struct take_cpu_down_param {
static int __ref take_cpu_down(void *_param)
{
struct take_cpu_down_param *param = _param;
+ unsigned int cpu = (unsigned int)(param->hcpu);
int err;

/* Ensure this CPU doesn't handle any more interrupts. */
+ trace_cpu_hotplug_disable_start(cpu);
err = __cpu_disable();
+ trace_cpu_hotplug_disable_end(cpu);
if (err < 0)
return err;

@@ -256,7 +262,9 @@ static int __ref _cpu_down(unsigned int cpu, int
tasks_frozen)
cpu_relax();

/* This actually kills the CPU. */
+ trace_cpu_hotplug_die_start(cpu);
__cpu_die(cpu);
+ trace_cpu_hotplug_die_end(cpu);

/* CPU is completely dead: tell everyone. Too late to complain. */
cpu_notify_nofail(CPU_DEAD | mod, hcpu);
@@ -276,6 +284,8 @@ int __ref cpu_down(unsigned int cpu)

cpu_maps_update_begin();

+ trace_cpu_hotplug_down_start(cpu);
+
if (cpu_hotplug_disabled) {
err = -EBUSY;
goto out;
@@ -284,6 +294,8 @@ int __ref cpu_down(unsigned int cpu)
err = _cpu_down(cpu, 0);

out:
+ trace_cpu_hotplug_down_end(cpu);
+
cpu_maps_update_done();
return err;
}
@@ -310,7 +322,9 @@ static int __cpuinit _cpu_up(unsigned int cpu, int
tasks_frozen)
}

/* Arch-specific enabling code. */
+ trace_cpu_hotplug_arch_up_start(cpu);
ret = __cpu_up(cpu);
+ trace_cpu_hotplug_arch_up_end(cpu);
if (ret != 0)
goto out_notify;
BUG_ON(!cpu_online(cpu));
@@ -369,6 +383,8 @@ int __cpuinit cpu_up(unsigned int cpu)

cpu_maps_update_begin();

+ trace_cpu_hotplug_up_start(cpu);
+
if (cpu_hotplug_disabled) {
err = -EBUSY;
goto out;
@@ -377,6 +393,8 @@ int __cpuinit cpu_up(unsigned int cpu)
err = _cpu_up(cpu, 0);

out:
+ trace_cpu_hotplug_up_end(cpu);
+
cpu_maps_update_done();
return err;
}
--
1.7.1

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