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cpu/hotplug: Add cpuhp_latency trace event

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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: Prasad Sodagudi <psodagud@codeaurora.org>
Signed-off-by: Elliot Berman <eberman@codeaurora.org>
This commit is contained in:
Prasad Sodagudi 2017-10-13 15:28:58 -07:00 committed by Elliot Berman
parent 243513a690
commit d49e1b840c
2 changed files with 38 additions and 0 deletions
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29
include/trace/events/cpuhp.h
View File

@ -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 */

9
kernel/cpu.c
View File

@ -35,6 +35,7 @@
#include <trace/events/power.h>
#define CREATE_TRACE_POINTS
#include <trace/events/cpuhp.h>
#include <linux/sched/clock.h>
#include "smpboot.h"
@ -969,6 +970,7 @@ 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;
@ -977,6 +979,8 @@ 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;
@ -1015,6 +1019,7 @@ 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
@ -1100,8 +1105,11 @@ 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;
@ -1149,6 +1157,7 @@ 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();
arch_smt_update();
return ret;