git.oblomov.eu Git - linux-2.6/blob - kernel/trace/trace_sched_switch.c

   1 /*
   2  * trace context switch
   3  *
   4  * Copyright (C) 2007 Steven Rostedt <srostedt@redhat.com>
   5  *
   6  */
   7 #include <linux/module.h>
   8 #include <linux/fs.h>
   9 #include <linux/debugfs.h>
  10 #include <linux/kallsyms.h>
  11 #include <linux/uaccess.h>
  12 #include <linux/ftrace.h>
  13 #include <trace/sched.h>
  14
  15 #include "trace.h"
  16
  17 static struct trace_array       *ctx_trace;
  18 static int __read_mostly        tracer_enabled;
  19 static atomic_t                 sched_ref;
  20 static DEFINE_MUTEX(tracepoint_mutex);
  21
  22 static void
  23 probe_sched_switch(struct rq *__rq, struct task_struct *prev,
  24                         struct task_struct *next)
  25 {
  26         struct trace_array_cpu *data;
  27         unsigned long flags;
  28         int cpu;
  29         int pc;
  30
  31         if (!atomic_read(&sched_ref))
  32                 return;
  33
  34         tracing_record_cmdline(prev);
  35         tracing_record_cmdline(next);
  36
  37         if (!tracer_enabled)
  38                 return;
  39
  40         pc = preempt_count();
  41         local_irq_save(flags);
  42         cpu = raw_smp_processor_id();
  43         data = ctx_trace->data[cpu];
  44
  45         if (likely(!atomic_read(&data->disabled)))
  46                 tracing_sched_switch_trace(ctx_trace, data, prev, next, flags, pc);
  47
  48         local_irq_restore(flags);
  49 }
  50
  51 static void
  52 probe_sched_wakeup(struct rq *__rq, struct task_struct *wakee)
  53 {
  54         struct trace_array_cpu *data;
  55         unsigned long flags;
  56         int cpu, pc;
  57
  58         if (!likely(tracer_enabled))
  59                 return;
  60
  61         pc = preempt_count();
  62         tracing_record_cmdline(current);
  63
  64         local_irq_save(flags);
  65         cpu = raw_smp_processor_id();
  66         data = ctx_trace->data[cpu];
  67
  68         if (likely(!atomic_read(&data->disabled)))
  69                 tracing_sched_wakeup_trace(ctx_trace, data, wakee, current,
  70                                            flags, pc);
  71
  72         local_irq_restore(flags);
  73 }
  74
  75 static void sched_switch_reset(struct trace_array *tr)
  76 {
  77         int cpu;
  78
  79         tr->time_start = ftrace_now(tr->cpu);
  80
  81         for_each_online_cpu(cpu)
  82                 tracing_reset(tr, cpu);
  83 }
  84
  85 static int tracing_sched_register(void)
  86 {
  87         int ret;
  88
  89         ret = register_trace_sched_wakeup(probe_sched_wakeup);
  90         if (ret) {
  91                 pr_info("wakeup trace: Couldn't activate tracepoint"
  92                         " probe to kernel_sched_wakeup\n");
  93                 return ret;
  94         }
  95
  96         ret = register_trace_sched_wakeup_new(probe_sched_wakeup);
  97         if (ret) {
  98                 pr_info("wakeup trace: Couldn't activate tracepoint"
  99                         " probe to kernel_sched_wakeup_new\n");
 100                 goto fail_deprobe;
 101         }
 102
 103         ret = register_trace_sched_switch(probe_sched_switch);
 104         if (ret) {
 105                 pr_info("sched trace: Couldn't activate tracepoint"
 106                         " probe to kernel_sched_schedule\n");
 107                 goto fail_deprobe_wake_new;
 108         }
 109
 110         return ret;
 111 fail_deprobe_wake_new:
 112         unregister_trace_sched_wakeup_new(probe_sched_wakeup);
 113 fail_deprobe:
 114         unregister_trace_sched_wakeup(probe_sched_wakeup);
 115         return ret;
 116 }
 117
 118 static void tracing_sched_unregister(void)
 119 {
 120         unregister_trace_sched_switch(probe_sched_switch);
 121         unregister_trace_sched_wakeup_new(probe_sched_wakeup);
 122         unregister_trace_sched_wakeup(probe_sched_wakeup);
 123 }
 124
 125 static void tracing_start_sched_switch(void)
 126 {
 127         long ref;
 128
 129         mutex_lock(&tracepoint_mutex);
 130         ref = atomic_inc_return(&sched_ref);
 131         if (ref == 1)
 132                 tracing_sched_register();
 133         mutex_unlock(&tracepoint_mutex);
 134 }
 135
 136 static void tracing_stop_sched_switch(void)
 137 {
 138         long ref;
 139
 140         mutex_lock(&tracepoint_mutex);
 141         ref = atomic_dec_and_test(&sched_ref);
 142         if (ref)
 143                 tracing_sched_unregister();
 144         mutex_unlock(&tracepoint_mutex);
 145 }
 146
 147 void tracing_start_cmdline_record(void)
 148 {
 149         tracing_start_sched_switch();
 150 }
 151
 152 void tracing_stop_cmdline_record(void)
 153 {
 154         tracing_stop_sched_switch();
 155 }
 156
 157 static void start_sched_trace(struct trace_array *tr)
 158 {
 159         sched_switch_reset(tr);
 160         tracing_start_cmdline_record();
 161         tracer_enabled = 1;
 162 }
 163
 164 static void stop_sched_trace(struct trace_array *tr)
 165 {
 166         tracer_enabled = 0;
 167         tracing_stop_cmdline_record();
 168 }
 169
 170 static void sched_switch_trace_init(struct trace_array *tr)
 171 {
 172         ctx_trace = tr;
 173
 174         if (tr->ctrl)
 175                 start_sched_trace(tr);
 176 }
 177
 178 static void sched_switch_trace_reset(struct trace_array *tr)
 179 {
 180         if (tr->ctrl)
 181                 stop_sched_trace(tr);
 182 }
 183
 184 static void sched_switch_trace_ctrl_update(struct trace_array *tr)
 185 {
 186         /* When starting a new trace, reset the buffers */
 187         if (tr->ctrl)
 188                 start_sched_trace(tr);
 189         else
 190                 stop_sched_trace(tr);
 191 }
 192
 193 static struct tracer sched_switch_trace __read_mostly =
 194 {
 195         .name           = "sched_switch",
 196         .init           = sched_switch_trace_init,
 197         .reset          = sched_switch_trace_reset,
 198         .ctrl_update    = sched_switch_trace_ctrl_update,
 199 #ifdef CONFIG_FTRACE_SELFTEST
 200         .selftest    = trace_selftest_startup_sched_switch,
 201 #endif
 202 };
 203
 204 __init static int init_sched_switch_trace(void)
 205 {
 206         return register_tracer(&sched_switch_trace);
 207 }
 208 device_initcall(init_sched_switch_trace);