402 lines
8.5 KiB
C
402 lines
8.5 KiB
C
/*
|
|
* trace task wakeup timings
|
|
*
|
|
* Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
|
|
* Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
|
|
*
|
|
* Based on code from the latency_tracer, that is:
|
|
*
|
|
* Copyright (C) 2004-2006 Ingo Molnar
|
|
* Copyright (C) 2004 William Lee Irwin III
|
|
*/
|
|
#include <linux/module.h>
|
|
#include <linux/fs.h>
|
|
#include <linux/debugfs.h>
|
|
#include <linux/kallsyms.h>
|
|
#include <linux/uaccess.h>
|
|
#include <linux/ftrace.h>
|
|
#include <trace/sched.h>
|
|
|
|
#include "trace.h"
|
|
|
|
static struct trace_array *wakeup_trace;
|
|
static int __read_mostly tracer_enabled;
|
|
|
|
static struct task_struct *wakeup_task;
|
|
static int wakeup_cpu;
|
|
static unsigned wakeup_prio = -1;
|
|
|
|
static raw_spinlock_t wakeup_lock =
|
|
(raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
|
|
|
|
static void __wakeup_reset(struct trace_array *tr);
|
|
|
|
#ifdef CONFIG_FUNCTION_TRACER
|
|
/*
|
|
* irqsoff uses its own tracer function to keep the overhead down:
|
|
*/
|
|
static void
|
|
wakeup_tracer_call(unsigned long ip, unsigned long parent_ip)
|
|
{
|
|
struct trace_array *tr = wakeup_trace;
|
|
struct trace_array_cpu *data;
|
|
unsigned long flags;
|
|
long disabled;
|
|
int resched;
|
|
int cpu;
|
|
int pc;
|
|
|
|
if (likely(!wakeup_task))
|
|
return;
|
|
|
|
pc = preempt_count();
|
|
resched = ftrace_preempt_disable();
|
|
|
|
cpu = raw_smp_processor_id();
|
|
data = tr->data[cpu];
|
|
disabled = atomic_inc_return(&data->disabled);
|
|
if (unlikely(disabled != 1))
|
|
goto out;
|
|
|
|
local_irq_save(flags);
|
|
__raw_spin_lock(&wakeup_lock);
|
|
|
|
if (unlikely(!wakeup_task))
|
|
goto unlock;
|
|
|
|
/*
|
|
* The task can't disappear because it needs to
|
|
* wake up first, and we have the wakeup_lock.
|
|
*/
|
|
if (task_cpu(wakeup_task) != cpu)
|
|
goto unlock;
|
|
|
|
trace_function(tr, data, ip, parent_ip, flags, pc);
|
|
|
|
unlock:
|
|
__raw_spin_unlock(&wakeup_lock);
|
|
local_irq_restore(flags);
|
|
|
|
out:
|
|
atomic_dec(&data->disabled);
|
|
|
|
ftrace_preempt_enable(resched);
|
|
}
|
|
|
|
static struct ftrace_ops trace_ops __read_mostly =
|
|
{
|
|
.func = wakeup_tracer_call,
|
|
};
|
|
#endif /* CONFIG_FUNCTION_TRACER */
|
|
|
|
/*
|
|
* Should this new latency be reported/recorded?
|
|
*/
|
|
static int report_latency(cycle_t delta)
|
|
{
|
|
if (tracing_thresh) {
|
|
if (delta < tracing_thresh)
|
|
return 0;
|
|
} else {
|
|
if (delta <= tracing_max_latency)
|
|
return 0;
|
|
}
|
|
return 1;
|
|
}
|
|
|
|
static void notrace
|
|
probe_wakeup_sched_switch(struct rq *rq, struct task_struct *prev,
|
|
struct task_struct *next)
|
|
{
|
|
unsigned long latency = 0, t0 = 0, t1 = 0;
|
|
struct trace_array_cpu *data;
|
|
cycle_t T0, T1, delta;
|
|
unsigned long flags;
|
|
long disabled;
|
|
int cpu;
|
|
int pc;
|
|
|
|
tracing_record_cmdline(prev);
|
|
|
|
if (unlikely(!tracer_enabled))
|
|
return;
|
|
|
|
/*
|
|
* When we start a new trace, we set wakeup_task to NULL
|
|
* and then set tracer_enabled = 1. We want to make sure
|
|
* that another CPU does not see the tracer_enabled = 1
|
|
* and the wakeup_task with an older task, that might
|
|
* actually be the same as next.
|
|
*/
|
|
smp_rmb();
|
|
|
|
if (next != wakeup_task)
|
|
return;
|
|
|
|
pc = preempt_count();
|
|
|
|
/* The task we are waiting for is waking up */
|
|
data = wakeup_trace->data[wakeup_cpu];
|
|
|
|
/* disable local data, not wakeup_cpu data */
|
|
cpu = raw_smp_processor_id();
|
|
disabled = atomic_inc_return(&wakeup_trace->data[cpu]->disabled);
|
|
if (likely(disabled != 1))
|
|
goto out;
|
|
|
|
local_irq_save(flags);
|
|
__raw_spin_lock(&wakeup_lock);
|
|
|
|
/* We could race with grabbing wakeup_lock */
|
|
if (unlikely(!tracer_enabled || next != wakeup_task))
|
|
goto out_unlock;
|
|
|
|
trace_function(wakeup_trace, data, CALLER_ADDR1, CALLER_ADDR2, flags, pc);
|
|
|
|
/*
|
|
* usecs conversion is slow so we try to delay the conversion
|
|
* as long as possible:
|
|
*/
|
|
T0 = data->preempt_timestamp;
|
|
T1 = ftrace_now(cpu);
|
|
delta = T1-T0;
|
|
|
|
if (!report_latency(delta))
|
|
goto out_unlock;
|
|
|
|
latency = nsecs_to_usecs(delta);
|
|
|
|
tracing_max_latency = delta;
|
|
t0 = nsecs_to_usecs(T0);
|
|
t1 = nsecs_to_usecs(T1);
|
|
|
|
update_max_tr(wakeup_trace, wakeup_task, wakeup_cpu);
|
|
|
|
out_unlock:
|
|
__wakeup_reset(wakeup_trace);
|
|
__raw_spin_unlock(&wakeup_lock);
|
|
local_irq_restore(flags);
|
|
out:
|
|
atomic_dec(&wakeup_trace->data[cpu]->disabled);
|
|
}
|
|
|
|
static void __wakeup_reset(struct trace_array *tr)
|
|
{
|
|
struct trace_array_cpu *data;
|
|
int cpu;
|
|
|
|
for_each_possible_cpu(cpu) {
|
|
data = tr->data[cpu];
|
|
tracing_reset(tr, cpu);
|
|
}
|
|
|
|
wakeup_cpu = -1;
|
|
wakeup_prio = -1;
|
|
|
|
if (wakeup_task)
|
|
put_task_struct(wakeup_task);
|
|
|
|
wakeup_task = NULL;
|
|
}
|
|
|
|
static void wakeup_reset(struct trace_array *tr)
|
|
{
|
|
unsigned long flags;
|
|
|
|
local_irq_save(flags);
|
|
__raw_spin_lock(&wakeup_lock);
|
|
__wakeup_reset(tr);
|
|
__raw_spin_unlock(&wakeup_lock);
|
|
local_irq_restore(flags);
|
|
}
|
|
|
|
static void
|
|
probe_wakeup(struct rq *rq, struct task_struct *p, int success)
|
|
{
|
|
int cpu = smp_processor_id();
|
|
unsigned long flags;
|
|
long disabled;
|
|
int pc;
|
|
|
|
if (likely(!tracer_enabled))
|
|
return;
|
|
|
|
tracing_record_cmdline(p);
|
|
tracing_record_cmdline(current);
|
|
|
|
if (likely(!rt_task(p)) ||
|
|
p->prio >= wakeup_prio ||
|
|
p->prio >= current->prio)
|
|
return;
|
|
|
|
pc = preempt_count();
|
|
disabled = atomic_inc_return(&wakeup_trace->data[cpu]->disabled);
|
|
if (unlikely(disabled != 1))
|
|
goto out;
|
|
|
|
/* interrupts should be off from try_to_wake_up */
|
|
__raw_spin_lock(&wakeup_lock);
|
|
|
|
/* check for races. */
|
|
if (!tracer_enabled || p->prio >= wakeup_prio)
|
|
goto out_locked;
|
|
|
|
/* reset the trace */
|
|
__wakeup_reset(wakeup_trace);
|
|
|
|
wakeup_cpu = task_cpu(p);
|
|
wakeup_prio = p->prio;
|
|
|
|
wakeup_task = p;
|
|
get_task_struct(wakeup_task);
|
|
|
|
local_save_flags(flags);
|
|
|
|
wakeup_trace->data[wakeup_cpu]->preempt_timestamp = ftrace_now(cpu);
|
|
trace_function(wakeup_trace, wakeup_trace->data[wakeup_cpu],
|
|
CALLER_ADDR1, CALLER_ADDR2, flags, pc);
|
|
|
|
out_locked:
|
|
__raw_spin_unlock(&wakeup_lock);
|
|
out:
|
|
atomic_dec(&wakeup_trace->data[cpu]->disabled);
|
|
}
|
|
|
|
/*
|
|
* save_tracer_enabled is used to save the state of the tracer_enabled
|
|
* variable when we disable it when we open a trace output file.
|
|
*/
|
|
static int save_tracer_enabled;
|
|
|
|
static void start_wakeup_tracer(struct trace_array *tr)
|
|
{
|
|
int ret;
|
|
|
|
ret = register_trace_sched_wakeup(probe_wakeup);
|
|
if (ret) {
|
|
pr_info("wakeup trace: Couldn't activate tracepoint"
|
|
" probe to kernel_sched_wakeup\n");
|
|
return;
|
|
}
|
|
|
|
ret = register_trace_sched_wakeup_new(probe_wakeup);
|
|
if (ret) {
|
|
pr_info("wakeup trace: Couldn't activate tracepoint"
|
|
" probe to kernel_sched_wakeup_new\n");
|
|
goto fail_deprobe;
|
|
}
|
|
|
|
ret = register_trace_sched_switch(probe_wakeup_sched_switch);
|
|
if (ret) {
|
|
pr_info("sched trace: Couldn't activate tracepoint"
|
|
" probe to kernel_sched_schedule\n");
|
|
goto fail_deprobe_wake_new;
|
|
}
|
|
|
|
wakeup_reset(tr);
|
|
|
|
/*
|
|
* Don't let the tracer_enabled = 1 show up before
|
|
* the wakeup_task is reset. This may be overkill since
|
|
* wakeup_reset does a spin_unlock after setting the
|
|
* wakeup_task to NULL, but I want to be safe.
|
|
* This is a slow path anyway.
|
|
*/
|
|
smp_wmb();
|
|
|
|
register_ftrace_function(&trace_ops);
|
|
|
|
if (tracing_is_enabled()) {
|
|
tracer_enabled = 1;
|
|
save_tracer_enabled = 1;
|
|
} else {
|
|
tracer_enabled = 0;
|
|
save_tracer_enabled = 0;
|
|
}
|
|
|
|
return;
|
|
fail_deprobe_wake_new:
|
|
unregister_trace_sched_wakeup_new(probe_wakeup);
|
|
fail_deprobe:
|
|
unregister_trace_sched_wakeup(probe_wakeup);
|
|
}
|
|
|
|
static void stop_wakeup_tracer(struct trace_array *tr)
|
|
{
|
|
tracer_enabled = 0;
|
|
save_tracer_enabled = 0;
|
|
unregister_ftrace_function(&trace_ops);
|
|
unregister_trace_sched_switch(probe_wakeup_sched_switch);
|
|
unregister_trace_sched_wakeup_new(probe_wakeup);
|
|
unregister_trace_sched_wakeup(probe_wakeup);
|
|
}
|
|
|
|
static int wakeup_tracer_init(struct trace_array *tr)
|
|
{
|
|
wakeup_trace = tr;
|
|
start_wakeup_tracer(tr);
|
|
return 0;
|
|
}
|
|
|
|
static void wakeup_tracer_reset(struct trace_array *tr)
|
|
{
|
|
stop_wakeup_tracer(tr);
|
|
/* make sure we put back any tasks we are tracing */
|
|
wakeup_reset(tr);
|
|
}
|
|
|
|
static void wakeup_tracer_start(struct trace_array *tr)
|
|
{
|
|
wakeup_reset(tr);
|
|
tracer_enabled = 1;
|
|
save_tracer_enabled = 1;
|
|
}
|
|
|
|
static void wakeup_tracer_stop(struct trace_array *tr)
|
|
{
|
|
tracer_enabled = 0;
|
|
save_tracer_enabled = 0;
|
|
}
|
|
|
|
static void wakeup_tracer_open(struct trace_iterator *iter)
|
|
{
|
|
/* stop the trace while dumping */
|
|
tracer_enabled = 0;
|
|
}
|
|
|
|
static void wakeup_tracer_close(struct trace_iterator *iter)
|
|
{
|
|
/* forget about any processes we were recording */
|
|
if (save_tracer_enabled) {
|
|
wakeup_reset(iter->tr);
|
|
tracer_enabled = 1;
|
|
}
|
|
}
|
|
|
|
static struct tracer wakeup_tracer __read_mostly =
|
|
{
|
|
.name = "wakeup",
|
|
.init = wakeup_tracer_init,
|
|
.reset = wakeup_tracer_reset,
|
|
.start = wakeup_tracer_start,
|
|
.stop = wakeup_tracer_stop,
|
|
.open = wakeup_tracer_open,
|
|
.close = wakeup_tracer_close,
|
|
.print_max = 1,
|
|
#ifdef CONFIG_FTRACE_SELFTEST
|
|
.selftest = trace_selftest_startup_wakeup,
|
|
#endif
|
|
};
|
|
|
|
__init static int init_wakeup_tracer(void)
|
|
{
|
|
int ret;
|
|
|
|
ret = register_tracer(&wakeup_tracer);
|
|
if (ret)
|
|
return ret;
|
|
|
|
return 0;
|
|
}
|
|
device_initcall(init_wakeup_tracer);
|