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>
116 lines
2.4 KiB
C
116 lines
2.4 KiB
C
/*
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* trace context switch
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*
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* Copyright (C) 2007 Steven Rostedt <srostedt@redhat.com>
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*
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*/
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#include <linux/module.h>
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#include <linux/fs.h>
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#include <linux/debugfs.h>
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#include <linux/kallsyms.h>
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#include <linux/uaccess.h>
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#include <linux/marker.h>
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#include <linux/ftrace.h>
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#include "trace.h"
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static struct trace_array *ctx_trace;
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static int __read_mostly tracer_enabled;
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static void notrace
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ctx_switch_func(struct task_struct *prev, struct task_struct *next)
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{
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struct trace_array *tr = ctx_trace;
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struct trace_array_cpu *data;
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unsigned long flags;
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long disabled;
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int cpu;
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if (!tracer_enabled)
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return;
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raw_local_irq_save(flags);
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cpu = raw_smp_processor_id();
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data = tr->data[cpu];
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disabled = atomic_inc_return(&data->disabled);
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if (likely(disabled == 1))
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tracing_sched_switch_trace(tr, data, prev, next, flags);
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atomic_dec(&data->disabled);
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raw_local_irq_restore(flags);
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}
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void ftrace_ctx_switch(struct task_struct *prev, struct task_struct *next)
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{
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tracing_record_cmdline(prev);
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/*
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* If tracer_switch_func only points to the local
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* switch func, it still needs the ptr passed to it.
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*/
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ctx_switch_func(prev, next);
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/*
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* Chain to the wakeup tracer (this is a NOP if disabled):
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*/
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wakeup_sched_switch(prev, next);
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}
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static notrace void sched_switch_reset(struct trace_array *tr)
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{
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int cpu;
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tr->time_start = now(tr->cpu);
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for_each_online_cpu(cpu)
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tracing_reset(tr->data[cpu]);
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}
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static notrace void start_sched_trace(struct trace_array *tr)
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{
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sched_switch_reset(tr);
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tracer_enabled = 1;
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}
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static notrace void stop_sched_trace(struct trace_array *tr)
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{
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tracer_enabled = 0;
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}
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static notrace void sched_switch_trace_init(struct trace_array *tr)
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{
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ctx_trace = tr;
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if (tr->ctrl)
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start_sched_trace(tr);
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}
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static notrace void sched_switch_trace_reset(struct trace_array *tr)
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{
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if (tr->ctrl)
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stop_sched_trace(tr);
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}
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static void sched_switch_trace_ctrl_update(struct trace_array *tr)
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{
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/* When starting a new trace, reset the buffers */
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if (tr->ctrl)
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start_sched_trace(tr);
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else
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stop_sched_trace(tr);
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}
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static struct tracer sched_switch_trace __read_mostly =
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{
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.name = "sched_switch",
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.init = sched_switch_trace_init,
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.reset = sched_switch_trace_reset,
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.ctrl_update = sched_switch_trace_ctrl_update,
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};
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__init static int init_sched_switch_trace(void)
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{
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return register_tracer(&sched_switch_trace);
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}
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device_initcall(init_sched_switch_trace);
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