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Commit a7c4ece7 authored by Prasad Sodagudi's avatar Prasad Sodagudi Committed by Venkata Narendra Kumar Gutta
Browse files

cpu/hotplug: Add cpuhp_latency trace event 



Add ftrace event trace_cpuhp_latency to track cpu
hotplug latency and this entry is useful in power,
performance and debug analysis.

Change-Id: Ie6b2a91027c665ccaf6325b0836bb629a4e91dd7
Signed-off-by: default avatarPrasad Sodagudi <psodagud@codeaurora.org>
Signed-off-by: default avatarVenkata Narendra Kumar Gutta <vnkgutta@codeaurora.org>
parent cb30afd5

include/trace/events/cpuhp.h

+29 −0
Original line number Diff line number Diff line
@@ -6,6 +6,7 @@ 
#define _TRACE_CPUHP_H



#include <linux/tracepoint.h>

#include <linux/sched/clock.h>



TRACE_EVENT(cpuhp_enter,
@@ -89,6 +90,34 @@ TRACE_EVENT(cpuhp_exit, 
		  __entry->cpu, __entry->state, __entry->idx,  __entry->ret)

);



TRACE_EVENT(cpuhp_latency,



	TP_PROTO(unsigned int cpu, unsigned int state,

		 u64 start_time,  int ret),



	TP_ARGS(cpu, state, start_time, ret),



	TP_STRUCT__entry(

		__field(unsigned int,	cpu)

		__field(unsigned int,	state)

		__field(u64,		time)

		__field(int,		ret)

	),



	TP_fast_assign(

		__entry->cpu	= cpu;

		__entry->state	= state;

		__entry->time	= div64_u64(sched_clock() - start_time, 1000);

		__entry->ret	= ret;

	),



	TP_printk(" cpu:%d state:%s latency:%llu USEC ret: %d",

		__entry->cpu, __entry->state ? "online" : "offline",

		__entry->time, __entry->ret)

);







#endif



/* This part must be outside protection */

kernel/cpu.c

+9 −0
Original line number Diff line number Diff line
@@ -33,6 +33,7 @@ 
#include <trace/events/power.h>

#define CREATE_TRACE_POINTS

#include <trace/events/cpuhp.h>

#include <linux/sched/clock.h>



#include "smpboot.h"
@@ -931,6 +932,7 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen, 
{

	struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);

	int prev_state, ret = 0;

	u64 start_time = 0;



	if (num_online_cpus() == 1)

		return -EBUSY;
@@ -939,6 +941,8 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen, 
		return -EINVAL;



	cpus_write_lock();

	if (trace_cpuhp_latency_enabled())

		start_time = sched_clock();



	cpuhp_tasks_frozen = tasks_frozen;
@@ -977,6 +981,7 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen, 
	}



out:

	trace_cpuhp_latency(cpu, 0, start_time, ret);

	cpus_write_unlock();

	/*

	 * Do post unplug cleanup. This is still protected against
@@ -1061,8 +1066,11 @@ static int _cpu_up(unsigned int cpu, int tasks_frozen, enum cpuhp_state target) 
	struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);

	struct task_struct *idle;

	int ret = 0;

	u64 start_time = 0;



	cpus_write_lock();

	if (trace_cpuhp_latency_enabled())

		start_time = sched_clock();



	if (!cpu_present(cpu)) {

		ret = -EINVAL;
@@ -1110,6 +1118,7 @@ static int _cpu_up(unsigned int cpu, int tasks_frozen, enum cpuhp_state target) 
	target = min((int)target, CPUHP_BRINGUP_CPU);

	ret = cpuhp_up_callbacks(cpu, st, target);

out:

	trace_cpuhp_latency(cpu, 1, start_time, ret);

	cpus_write_unlock();

	return ret;

}