kernel/trace/ring_buffer_benchmark.c

   1 /*
   2  * ring buffer tester and benchmark
   3  *
   4  * Copyright (C) 2009 Steven Rostedt <srostedt@redhat.com>
   5  */
   6 #include <linux/ring_buffer.h>
   7 #include <linux/completion.h>
   8 #include <linux/kthread.h>
   9 #include <linux/module.h>
  10 #include <linux/time.h>
  11
  12 struct rb_page {
  13         u64             ts;
  14         local_t         commit;
  15         char            data[4080];
  16 };
  17
  18 /* run time and sleep time in seconds */
  19 #define RUN_TIME        10
  20 #define SLEEP_TIME      10
  21
  22 /* number of events for writer to wake up the reader */
  23 static int wakeup_interval = 100;
  24
  25 static int reader_finish;
  26 static struct completion read_start;
  27 static struct completion read_done;
  28
  29 static struct ring_buffer *buffer;
  30 static struct task_struct *producer;
  31 static struct task_struct *consumer;
  32 static unsigned long read;
  33
  34 static int disable_reader;
  35 module_param(disable_reader, uint, 0644);
  36 MODULE_PARM_DESC(disable_reader, "only run producer");
  37
  38 static int read_events;
  39
  40 static int kill_test;
  41
  42 #define KILL_TEST()                             \
  43         do {                                    \
  44                 if (!kill_test) {               \
  45                         kill_test = 1;          \
  46                         WARN_ON(1);             \
  47                 }                               \
  48         } while (0)
  49
  50 enum event_status {
  51         EVENT_FOUND,
  52         EVENT_DROPPED,
  53 };
  54
  55 static enum event_status read_event(int cpu)
  56 {
  57         struct ring_buffer_event *event;
  58         int *entry;
  59         u64 ts;
  60
  61         event = ring_buffer_consume(buffer, cpu, &ts);
  62         if (!event)
  63                 return EVENT_DROPPED;
  64
  65         entry = ring_buffer_event_data(event);
  66         if (*entry != cpu) {
  67                 KILL_TEST();
  68                 return EVENT_DROPPED;
  69         }
  70
  71         read++;
  72         return EVENT_FOUND;
  73 }
  74
  75 static enum event_status read_page(int cpu)
  76 {
  77         struct ring_buffer_event *event;
  78         struct rb_page *rpage;
  79         unsigned long commit;
  80         void *bpage;
  81         int *entry;
  82         int ret;
  83         int inc;
  84         int i;
  85
  86         bpage = ring_buffer_alloc_read_page(buffer);
  87         if (!bpage)
  88                 return EVENT_DROPPED;
  89
  90         ret = ring_buffer_read_page(buffer, &bpage, PAGE_SIZE, cpu, 1);
  91         if (ret >= 0) {
  92                 rpage = bpage;
  93                 commit = local_read(&rpage->commit);
  94                 for (i = 0; i < commit && !kill_test; i += inc) {
  95
  96                         if (i >= (PAGE_SIZE - offsetof(struct rb_page, data))) {
  97                                 KILL_TEST();
  98                                 break;
  99                         }
 100
 101                         inc = -1;
 102                         event = (void *)&rpage->data[i];
 103                         switch (event->type_len) {
 104                         case RINGBUF_TYPE_PADDING:
 105                                 /* We don't expect any padding */
 106                                 KILL_TEST();
 107                                 break;
 108                         case RINGBUF_TYPE_TIME_EXTEND:
 109                                 inc = 8;
 110                                 break;
 111                         case 0:
 112                                 entry = ring_buffer_event_data(event);
 113                                 if (*entry != cpu) {
 114                                         KILL_TEST();
 115                                         break;
 116                                 }
 117                                 read++;
 118                                 if (!event->array[0]) {
 119                                         KILL_TEST();
 120                                         break;
 121                                 }
 122                                 inc = event->array[0];
 123                                 break;
 124                         default:
 125                                 entry = ring_buffer_event_data(event);
 126                                 if (*entry != cpu) {
 127                                         KILL_TEST();
 128                                         break;
 129                                 }
 130                                 read++;
 131                                 inc = ((event->type_len + 1) * 4);
 132                         }
 133                         if (kill_test)
 134                                 break;
 135
 136                         if (inc <= 0) {
 137                                 KILL_TEST();
 138                                 break;
 139                         }
 140                 }
 141         }
 142         ring_buffer_free_read_page(buffer, bpage);
 143
 144         if (ret < 0)
 145                 return EVENT_DROPPED;
 146         return EVENT_FOUND;
 147 }
 148
 149 static void ring_buffer_consumer(void)
 150 {
 151         /* toggle between reading pages and events */
 152         read_events ^= 1;
 153
 154         read = 0;
 155         while (!reader_finish && !kill_test) {
 156                 int found;
 157
 158                 do {
 159                         int cpu;
 160
 161                         found = 0;
 162                         for_each_online_cpu(cpu) {
 163                                 enum event_status stat;
 164
 165                                 if (read_events)
 166                                         stat = read_event(cpu);
 167                                 else
 168                                         stat = read_page(cpu);
 169
 170                                 if (kill_test)
 171                                         break;
 172                                 if (stat == EVENT_FOUND)
 173                                         found = 1;
 174                         }
 175                 } while (found && !kill_test);
 176
 177                 set_current_state(TASK_INTERRUPTIBLE);
 178                 if (reader_finish)
 179                         break;
 180
 181                 schedule();
 182                 __set_current_state(TASK_RUNNING);
 183         }
 184         reader_finish = 0;
 185         complete(&read_done);
 186 }
 187
 188 static void ring_buffer_producer(void)
 189 {
 190         struct timeval start_tv;
 191         struct timeval end_tv;
 192         unsigned long long time;
 193         unsigned long long entries;
 194         unsigned long long overruns;
 195         unsigned long missed = 0;
 196         unsigned long hit = 0;
 197         unsigned long avg;
 198         int cnt = 0;
 199
 200         /*
 201          * Hammer the buffer for 10 secs (this may
 202          * make the system stall)
 203          */
 204         pr_info("Starting ring buffer hammer\n");
 205         do_gettimeofday(&start_tv);
 206         do {
 207                 struct ring_buffer_event *event;
 208                 int *entry;
 209
 210                 event = ring_buffer_lock_reserve(buffer, 10);
 211                 if (!event) {
 212                         missed++;
 213                 } else {
 214                         hit++;
 215                         entry = ring_buffer_event_data(event);
 216                         *entry = smp_processor_id();
 217                         ring_buffer_unlock_commit(buffer, event);
 218                 }
 219                 do_gettimeofday(&end_tv);
 220
 221                 if (consumer && !(++cnt % wakeup_interval))
 222                         wake_up_process(consumer);
 223
 224         } while (end_tv.tv_sec < (start_tv.tv_sec + RUN_TIME) && !kill_test);
 225         pr_info("End ring buffer hammer\n");
 226
 227         if (consumer) {
 228                 /* Init both completions here to avoid races */
 229                 init_completion(&read_start);
 230                 init_completion(&read_done);
 231                 /* the completions must be visible before the finish var */
 232                 smp_wmb();
 233                 reader_finish = 1;
 234                 /* finish var visible before waking up the consumer */
 235                 smp_wmb();
 236                 wake_up_process(consumer);
 237                 wait_for_completion(&read_done);
 238         }
 239
 240         time = end_tv.tv_sec - start_tv.tv_sec;
 241         time *= 1000000;
 242         time += (long long)((long)end_tv.tv_usec - (long)start_tv.tv_usec);
 243
 244         entries = ring_buffer_entries(buffer);
 245         overruns = ring_buffer_overruns(buffer);
 246
 247         if (kill_test)
 248                 pr_info("ERROR!\n");
 249         pr_info("Time:     %lld (usecs)\n", time);
 250         pr_info("Overruns: %lld\n", overruns);
 251         if (disable_reader)
 252                 pr_info("Read:     (reader disabled)\n");
 253         else
 254                 pr_info("Read:     %ld  (by %s)\n", read,
 255                         read_events ? "events" : "pages");
 256         pr_info("Entries:  %lld\n", entries);
 257         pr_info("Total:    %lld\n", entries + overruns + read);
 258         pr_info("Missed:   %ld\n", missed);
 259         pr_info("Hit:      %ld\n", hit);
 260
 261         do_div(time, 1000);
 262         if (time)
 263                 hit /= (long)time;
 264         else
 265                 pr_info("TIME IS ZERO??\n");
 266
 267         pr_info("Entries per millisec: %ld\n", hit);
 268
 269         if (hit) {
 270                 avg = 1000000 / hit;
 271                 pr_info("%ld ns per entry\n", avg);
 272         }
 273 }
 274
 275 static void wait_to_die(void)
 276 {
 277         set_current_state(TASK_INTERRUPTIBLE);
 278         while (!kthread_should_stop()) {
 279                 schedule();
 280                 set_current_state(TASK_INTERRUPTIBLE);
 281         }
 282         __set_current_state(TASK_RUNNING);
 283 }
 284
 285 static int ring_buffer_consumer_thread(void *arg)
 286 {
 287         while (!kthread_should_stop() && !kill_test) {
 288                 complete(&read_start);
 289
 290                 ring_buffer_consumer();
 291
 292                 set_current_state(TASK_INTERRUPTIBLE);
 293                 if (kthread_should_stop() || kill_test)
 294                         break;
 295
 296                 schedule();
 297                 __set_current_state(TASK_RUNNING);
 298         }
 299         __set_current_state(TASK_RUNNING);
 300
 301         if (kill_test)
 302                 wait_to_die();
 303
 304         return 0;
 305 }
 306
 307 static int ring_buffer_producer_thread(void *arg)
 308 {
 309         init_completion(&read_start);
 310
 311         while (!kthread_should_stop() && !kill_test) {
 312                 ring_buffer_reset(buffer);
 313
 314                 if (consumer) {
 315                         smp_wmb();
 316                         wake_up_process(consumer);
 317                         wait_for_completion(&read_start);
 318                 }
 319
 320                 ring_buffer_producer();
 321
 322                 pr_info("Sleeping for 10 secs\n");
 323                 set_current_state(TASK_INTERRUPTIBLE);
 324                 schedule_timeout(HZ * SLEEP_TIME);
 325                 __set_current_state(TASK_RUNNING);
 326         }
 327
 328         if (kill_test)
 329                 wait_to_die();
 330
 331         return 0;
 332 }
 333
 334 static int __init ring_buffer_benchmark_init(void)
 335 {
 336         int ret;
 337
 338         /* make a one meg buffer in overwite mode */
 339         buffer = ring_buffer_alloc(1000000, RB_FL_OVERWRITE);
 340         if (!buffer)
 341                 return -ENOMEM;
 342
 343         if (!disable_reader) {
 344                 consumer = kthread_create(ring_buffer_consumer_thread,
 345                                           NULL, "rb_consumer");
 346                 ret = PTR_ERR(consumer);
 347                 if (IS_ERR(consumer))
 348                         goto out_fail;
 349         }
 350
 351         producer = kthread_run(ring_buffer_producer_thread,
 352                                NULL, "rb_producer");
 353         ret = PTR_ERR(producer);
 354
 355         if (IS_ERR(producer))
 356                 goto out_kill;
 357
 358         return 0;
 359
 360  out_kill:
 361         if (consumer)
 362                 kthread_stop(consumer);
 363
 364  out_fail:
 365         ring_buffer_free(buffer);
 366         return ret;
 367 }
 368
 369 static void __exit ring_buffer_benchmark_exit(void)
 370 {
 371         kthread_stop(producer);
 372         if (consumer)
 373                 kthread_stop(consumer);
 374         ring_buffer_free(buffer);
 375 }
 376
 377 module_init(ring_buffer_benchmark_init);
 378 module_exit(ring_buffer_benchmark_exit);
 379
 380 MODULE_AUTHOR("Steven Rostedt");
 381 MODULE_DESCRIPTION("ring_buffer_benchmark");
 382 MODULE_LICENSE("GPL");