forked from Minki/linux
35e8e302e5
This patch adds context switch tracing, of the format of:
_------=> CPU#
/ _-----=> irqs-off
| / _----=> need-resched
|| / _---=> hardirq/softirq
||| / _--=> preempt-depth
|||| /
||||| delay
cmd pid ||||| time | pid:prio:state
\ / ||||| \ | /
swapper-0 1d..3 137us+: 0:140:R --> 2912:120
sshd-2912 1d..3 216us+: 2912:120:S --> 0:140
swapper-0 1d..3 261us+: 0:140:R --> 2912:120
bash-2920 0d..3 267us+: 2920:120:S --> 0:140
sshd-2912 1d..3 330us!: 2912:120:S --> 0:140
swapper-0 1d..3 2389us+: 0:140:R --> 2847:120
yum-upda-2847 1d..3 2411us!: 2847:120:S --> 0:140
swapper-0 0d..3 11089us+: 0:140:R --> 3139:120
gdm-bina-3139 0d..3 11113us!: 3139:120:S --> 0:140
swapper-0 1d..3 102328us+: 0:140:R --> 2847:120
yum-upda-2847 1d..3 102348us!: 2847:120:S --> 0:140
"sched_switch" is added to /debugfs/tracing/available_tracers
[ Eugene Teo <eugeneteo@kernel.sg: remove unused tracing_sched_switch_enabled ]
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
117 lines
2.4 KiB
C
117 lines
2.4 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/marker.h>
|
|
#include <linux/ftrace.h>
|
|
|
|
#include "trace.h"
|
|
|
|
static struct trace_array *ctx_trace;
|
|
static int __read_mostly tracer_enabled;
|
|
|
|
static void notrace
|
|
ctx_switch_func(struct task_struct *prev, struct task_struct *next)
|
|
{
|
|
struct trace_array *tr = ctx_trace;
|
|
struct trace_array_cpu *data;
|
|
unsigned long flags;
|
|
long disabled;
|
|
int cpu;
|
|
|
|
if (!tracer_enabled)
|
|
return;
|
|
|
|
raw_local_irq_save(flags);
|
|
cpu = raw_smp_processor_id();
|
|
data = tr->data[cpu];
|
|
disabled = atomic_inc_return(&data->disabled);
|
|
|
|
if (likely(disabled == 1))
|
|
tracing_sched_switch_trace(tr, data, prev, next, flags);
|
|
|
|
atomic_dec(&data->disabled);
|
|
raw_local_irq_restore(flags);
|
|
}
|
|
|
|
void ftrace_ctx_switch(struct task_struct *prev, struct task_struct *next)
|
|
{
|
|
tracing_record_cmdline(prev);
|
|
|
|
/*
|
|
* If tracer_switch_func only points to the local
|
|
* switch func, it still needs the ptr passed to it.
|
|
*/
|
|
ctx_switch_func(prev, next);
|
|
|
|
/*
|
|
* Chain to the wakeup tracer (this is a NOP if disabled):
|
|
*/
|
|
wakeup_sched_switch(prev, next);
|
|
}
|
|
|
|
static notrace void sched_switch_reset(struct trace_array *tr)
|
|
{
|
|
int cpu;
|
|
|
|
tr->time_start = now(tr->cpu);
|
|
|
|
for_each_online_cpu(cpu)
|
|
tracing_reset(tr->data[cpu]);
|
|
}
|
|
|
|
static notrace void start_sched_trace(struct trace_array *tr)
|
|
{
|
|
sched_switch_reset(tr);
|
|
tracer_enabled = 1;
|
|
}
|
|
|
|
static notrace void stop_sched_trace(struct trace_array *tr)
|
|
{
|
|
tracer_enabled = 0;
|
|
}
|
|
|
|
static notrace void sched_switch_trace_init(struct trace_array *tr)
|
|
{
|
|
ctx_trace = tr;
|
|
|
|
if (tr->ctrl)
|
|
start_sched_trace(tr);
|
|
}
|
|
|
|
static notrace void sched_switch_trace_reset(struct trace_array *tr)
|
|
{
|
|
if (tr->ctrl)
|
|
stop_sched_trace(tr);
|
|
}
|
|
|
|
static void sched_switch_trace_ctrl_update(struct trace_array *tr)
|
|
{
|
|
/* When starting a new trace, reset the buffers */
|
|
if (tr->ctrl)
|
|
start_sched_trace(tr);
|
|
else
|
|
stop_sched_trace(tr);
|
|
}
|
|
|
|
static struct tracer sched_switch_trace __read_mostly =
|
|
{
|
|
.name = "sched_switch",
|
|
.init = sched_switch_trace_init,
|
|
.reset = sched_switch_trace_reset,
|
|
.ctrl_update = sched_switch_trace_ctrl_update,
|
|
};
|
|
|
|
__init static int init_sched_switch_trace(void)
|
|
{
|
|
return register_tracer(&sched_switch_trace);
|
|
}
|
|
device_initcall(init_sched_switch_trace);
|