![Peter Zijlstra](/assets/img/avatar_default.png)
Impact: extend the wakeup tracepoint with the info whether the wakeup was real Add the information needed to distinguish 'real' wakeups from 'false' wakeups. Signed-off-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
241 lines
5.1 KiB
C
241 lines
5.1 KiB
C
/*
|
|
* trace context switch
|
|
*
|
|
* Copyright (C) 2007 Steven Rostedt <srostedt@redhat.com>
|
|
*
|
|
*/
|
|
#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 *ctx_trace;
|
|
static int __read_mostly tracer_enabled;
|
|
static int sched_ref;
|
|
static DEFINE_MUTEX(sched_register_mutex);
|
|
|
|
static void
|
|
probe_sched_switch(struct rq *__rq, struct task_struct *prev,
|
|
struct task_struct *next)
|
|
{
|
|
struct trace_array_cpu *data;
|
|
unsigned long flags;
|
|
int cpu;
|
|
int pc;
|
|
|
|
if (!sched_ref)
|
|
return;
|
|
|
|
tracing_record_cmdline(prev);
|
|
tracing_record_cmdline(next);
|
|
|
|
if (!tracer_enabled)
|
|
return;
|
|
|
|
pc = preempt_count();
|
|
local_irq_save(flags);
|
|
cpu = raw_smp_processor_id();
|
|
data = ctx_trace->data[cpu];
|
|
|
|
if (likely(!atomic_read(&data->disabled)))
|
|
tracing_sched_switch_trace(ctx_trace, data, prev, next, flags, pc);
|
|
|
|
local_irq_restore(flags);
|
|
}
|
|
|
|
static void
|
|
probe_sched_wakeup(struct rq *__rq, struct task_struct *wakee, int success)
|
|
{
|
|
struct trace_array_cpu *data;
|
|
unsigned long flags;
|
|
int cpu, pc;
|
|
|
|
if (!likely(tracer_enabled))
|
|
return;
|
|
|
|
pc = preempt_count();
|
|
tracing_record_cmdline(current);
|
|
|
|
local_irq_save(flags);
|
|
cpu = raw_smp_processor_id();
|
|
data = ctx_trace->data[cpu];
|
|
|
|
if (likely(!atomic_read(&data->disabled)))
|
|
tracing_sched_wakeup_trace(ctx_trace, data, wakee, current,
|
|
flags, pc);
|
|
|
|
local_irq_restore(flags);
|
|
}
|
|
|
|
static int tracing_sched_register(void)
|
|
{
|
|
int ret;
|
|
|
|
ret = register_trace_sched_wakeup(probe_sched_wakeup);
|
|
if (ret) {
|
|
pr_info("wakeup trace: Couldn't activate tracepoint"
|
|
" probe to kernel_sched_wakeup\n");
|
|
return ret;
|
|
}
|
|
|
|
ret = register_trace_sched_wakeup_new(probe_sched_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_sched_switch);
|
|
if (ret) {
|
|
pr_info("sched trace: Couldn't activate tracepoint"
|
|
" probe to kernel_sched_schedule\n");
|
|
goto fail_deprobe_wake_new;
|
|
}
|
|
|
|
return ret;
|
|
fail_deprobe_wake_new:
|
|
unregister_trace_sched_wakeup_new(probe_sched_wakeup);
|
|
fail_deprobe:
|
|
unregister_trace_sched_wakeup(probe_sched_wakeup);
|
|
return ret;
|
|
}
|
|
|
|
static void tracing_sched_unregister(void)
|
|
{
|
|
unregister_trace_sched_switch(probe_sched_switch);
|
|
unregister_trace_sched_wakeup_new(probe_sched_wakeup);
|
|
unregister_trace_sched_wakeup(probe_sched_wakeup);
|
|
}
|
|
|
|
static void tracing_start_sched_switch(void)
|
|
{
|
|
mutex_lock(&sched_register_mutex);
|
|
if (!(sched_ref++))
|
|
tracing_sched_register();
|
|
mutex_unlock(&sched_register_mutex);
|
|
}
|
|
|
|
static void tracing_stop_sched_switch(void)
|
|
{
|
|
mutex_lock(&sched_register_mutex);
|
|
if (!(--sched_ref))
|
|
tracing_sched_unregister();
|
|
mutex_unlock(&sched_register_mutex);
|
|
}
|
|
|
|
void tracing_start_cmdline_record(void)
|
|
{
|
|
tracing_start_sched_switch();
|
|
}
|
|
|
|
void tracing_stop_cmdline_record(void)
|
|
{
|
|
tracing_stop_sched_switch();
|
|
}
|
|
|
|
/**
|
|
* tracing_start_sched_switch_record - start tracing context switches
|
|
*
|
|
* Turns on context switch tracing for a tracer.
|
|
*/
|
|
void tracing_start_sched_switch_record(void)
|
|
{
|
|
if (unlikely(!ctx_trace)) {
|
|
WARN_ON(1);
|
|
return;
|
|
}
|
|
|
|
tracing_start_sched_switch();
|
|
|
|
mutex_lock(&sched_register_mutex);
|
|
tracer_enabled++;
|
|
mutex_unlock(&sched_register_mutex);
|
|
}
|
|
|
|
/**
|
|
* tracing_stop_sched_switch_record - start tracing context switches
|
|
*
|
|
* Turns off context switch tracing for a tracer.
|
|
*/
|
|
void tracing_stop_sched_switch_record(void)
|
|
{
|
|
mutex_lock(&sched_register_mutex);
|
|
tracer_enabled--;
|
|
WARN_ON(tracer_enabled < 0);
|
|
mutex_unlock(&sched_register_mutex);
|
|
|
|
tracing_stop_sched_switch();
|
|
}
|
|
|
|
/**
|
|
* tracing_sched_switch_assign_trace - assign a trace array for ctx switch
|
|
* @tr: trace array pointer to assign
|
|
*
|
|
* Some tracers might want to record the context switches in their
|
|
* trace. This function lets those tracers assign the trace array
|
|
* to use.
|
|
*/
|
|
void tracing_sched_switch_assign_trace(struct trace_array *tr)
|
|
{
|
|
ctx_trace = tr;
|
|
}
|
|
|
|
static void start_sched_trace(struct trace_array *tr)
|
|
{
|
|
tracing_reset_online_cpus(tr);
|
|
tracing_start_sched_switch_record();
|
|
}
|
|
|
|
static void stop_sched_trace(struct trace_array *tr)
|
|
{
|
|
tracing_stop_sched_switch_record();
|
|
}
|
|
|
|
static int sched_switch_trace_init(struct trace_array *tr)
|
|
{
|
|
ctx_trace = tr;
|
|
start_sched_trace(tr);
|
|
return 0;
|
|
}
|
|
|
|
static void sched_switch_trace_reset(struct trace_array *tr)
|
|
{
|
|
if (sched_ref)
|
|
stop_sched_trace(tr);
|
|
}
|
|
|
|
static void sched_switch_trace_start(struct trace_array *tr)
|
|
{
|
|
tracing_reset_online_cpus(tr);
|
|
tracing_start_sched_switch();
|
|
}
|
|
|
|
static void sched_switch_trace_stop(struct trace_array *tr)
|
|
{
|
|
tracing_stop_sched_switch();
|
|
}
|
|
|
|
static struct tracer sched_switch_trace __read_mostly =
|
|
{
|
|
.name = "sched_switch",
|
|
.init = sched_switch_trace_init,
|
|
.reset = sched_switch_trace_reset,
|
|
.start = sched_switch_trace_start,
|
|
.stop = sched_switch_trace_stop,
|
|
#ifdef CONFIG_FTRACE_SELFTEST
|
|
.selftest = trace_selftest_startup_sched_switch,
|
|
#endif
|
|
};
|
|
|
|
__init static int init_sched_switch_trace(void)
|
|
{
|
|
return register_tracer(&sched_switch_trace);
|
|
}
|
|
device_initcall(init_sched_switch_trace);
|
|
|