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/ktime.h>
  11 #include <asm/local.h>
  12
  13 struct rb_page {
  14         u64             ts;
  15         local_t         commit;
  16         char            data[4080];
  17 };
  18
  19 /* run time and sleep time in seconds */
  20 #define RUN_TIME        10ULL
  21 #define SLEEP_TIME      10
  22
  23 /* number of events for writer to wake up the reader */
  24 static int wakeup_interval = 100;
  25
  26 static int reader_finish;
  27 static struct completion read_start;
  28 static struct completion read_done;
  29
  30 static struct ring_buffer *buffer;
  31 static struct task_struct *producer;
  32 static struct task_struct *consumer;
  33 static unsigned long read;
  34
  35 static int disable_reader;
  36 module_param(disable_reader, uint, 0644);
  37 MODULE_PARM_DESC(disable_reader, "only run producer");
  38
  39 static int write_iteration = 50;
  40 module_param(write_iteration, uint, 0644);
  41 MODULE_PARM_DESC(write_iteration, "# of writes between timestamp readings");
  42
  43 static int producer_nice = MAX_NICE;
  44 static int consumer_nice = MAX_NICE;
  45
  46 static int producer_fifo = -1;
  47 static int consumer_fifo = -1;
  48
  49 module_param(producer_nice, uint, 0644);
  50 MODULE_PARM_DESC(producer_nice, "nice prio for producer");
  51
  52 module_param(consumer_nice, uint, 0644);
  53 MODULE_PARM_DESC(consumer_nice, "nice prio for consumer");
  54
  55 module_param(producer_fifo, uint, 0644);
  56 MODULE_PARM_DESC(producer_fifo, "fifo prio for producer");
  57
  58 module_param(consumer_fifo, uint, 0644);
  59 MODULE_PARM_DESC(consumer_fifo, "fifo prio for consumer");
  60
  61 static int read_events;
  62
  63 static int kill_test;
  64
  65 #define KILL_TEST()                             \
  66         do {                                    \
  67                 if (!kill_test) {               \
  68                         kill_test = 1;          \
  69                         WARN_ON(1);             \
  70                 }                               \
  71         } while (0)
  72
  73 enum event_status {
  74         EVENT_FOUND,
  75         EVENT_DROPPED,
  76 };
  77
  78 static enum event_status read_event(int cpu)
  79 {
  80         struct ring_buffer_event *event;
  81         int *entry;
  82         u64 ts;
  83
  84         event = ring_buffer_consume(buffer, cpu, &ts, NULL);
  85         if (!event)
  86                 return EVENT_DROPPED;
  87
  88         entry = ring_buffer_event_data(event);
  89         if (*entry != cpu) {
  90                 KILL_TEST();
  91                 return EVENT_DROPPED;
  92         }
  93
  94         read++;
  95         return EVENT_FOUND;
  96 }
  97
  98 static enum event_status read_page(int cpu)
  99 {
 100         struct ring_buffer_event *event;
 101         struct rb_page *rpage;
 102         unsigned long commit;
 103         void *bpage;
 104         int *entry;
 105         int ret;
 106         int inc;
 107         int i;
 108
 109         bpage = ring_buffer_alloc_read_page(buffer, cpu);
 110         if (!bpage)
 111                 return EVENT_DROPPED;
 112
 113         ret = ring_buffer_read_page(buffer, &bpage, PAGE_SIZE, cpu, 1);
 114         if (ret >= 0) {
 115                 rpage = bpage;
 116                 /* The commit may have missed event flags set, clear them */
 117                 commit = local_read(&rpage->commit) & 0xfffff;
 118                 for (i = 0; i < commit && !kill_test; i += inc) {
 119
 120                         if (i >= (PAGE_SIZE - offsetof(struct rb_page, data))) {
 121                                 KILL_TEST();
 122                                 break;
 123                         }
 124
 125                         inc = -1;
 126                         event = (void *)&rpage->data[i];
 127                         switch (event->type_len) {
 128                         case RINGBUF_TYPE_PADDING:
 129                                 /* failed writes may be discarded events */
 130                                 if (!event->time_delta)
 131                                         KILL_TEST();
 132                                 inc = event->array[0] + 4;
 133                                 break;
 134                         case RINGBUF_TYPE_TIME_EXTEND:
 135                                 inc = 8;
 136                                 break;
 137                         case 0:
 138                                 entry = ring_buffer_event_data(event);
 139                                 if (*entry != cpu) {
 140                                         KILL_TEST();
 141                                         break;
 142                                 }
 143                                 read++;
 144                                 if (!event->array[0]) {
 145                                         KILL_TEST();
 146                                         break;
 147                                 }
 148                                 inc = event->array[0] + 4;
 149                                 break;
 150                         default:
 151                                 entry = ring_buffer_event_data(event);
 152                                 if (*entry != cpu) {
 153                                         KILL_TEST();
 154                                         break;
 155                                 }
 156                                 read++;
 157                                 inc = ((event->type_len + 1) * 4);
 158                         }
 159                         if (kill_test)
 160                                 break;
 161
 162                         if (inc <= 0) {
 163                                 KILL_TEST();
 164                                 break;
 165                         }
 166                 }
 167         }
 168         ring_buffer_free_read_page(buffer, bpage);
 169
 170         if (ret < 0)
 171                 return EVENT_DROPPED;
 172         return EVENT_FOUND;
 173 }
 174
 175 static void ring_buffer_consumer(void)
 176 {
 177         /* toggle between reading pages and events */
 178         read_events ^= 1;
 179
 180         read = 0;
 181         while (!reader_finish && !kill_test) {
 182                 int found;
 183
 184                 do {
 185                         int cpu;
 186
 187                         found = 0;
 188                         for_each_online_cpu(cpu) {
 189                                 enum event_status stat;
 190
 191                                 if (read_events)
 192                                         stat = read_event(cpu);
 193                                 else
 194                                         stat = read_page(cpu);
 195
 196                                 if (kill_test)
 197                                         break;
 198                                 if (stat == EVENT_FOUND)
 199                                         found = 1;
 200                         }
 201                 } while (found && !kill_test);
 202
 203                 set_current_state(TASK_INTERRUPTIBLE);
 204                 if (reader_finish)
 205                         break;
 206
 207                 schedule();
 208         }
 209         reader_finish = 0;
 210         complete(&read_done);
 211 }
 212
 213 static void ring_buffer_producer(void)
 214 {
 215         ktime_t start_time, end_time, timeout;
 216         unsigned long long time;
 217         unsigned long long entries;
 218         unsigned long long overruns;
 219         unsigned long missed = 0;
 220         unsigned long hit = 0;
 221         unsigned long avg;
 222         int cnt = 0;
 223
 224         /*
 225          * Hammer the buffer for 10 secs (this may
 226          * make the system stall)
 227          */
 228         trace_printk("Starting ring buffer hammer\n");
 229         start_time = ktime_get();
 230         timeout = ktime_add_ns(start_time, RUN_TIME * NSEC_PER_SEC);
 231         do {
 232                 struct ring_buffer_event *event;
 233                 int *entry;
 234                 int i;
 235
 236                 for (i = 0; i < write_iteration; i++) {
 237                         event = ring_buffer_lock_reserve(buffer, 10);
 238                         if (!event) {
 239                                 missed++;
 240                         } else {
 241                                 hit++;
 242                                 entry = ring_buffer_event_data(event);
 243                                 *entry = smp_processor_id();
 244                                 ring_buffer_unlock_commit(buffer, event);
 245                         }
 246                 }
 247                 end_time = ktime_get();
 248
 249                 cnt++;
 250                 if (consumer && !(cnt % wakeup_interval))
 251                         wake_up_process(consumer);
 252
 253 #ifndef CONFIG_PREEMPT
 254                 /*
 255                  * If we are a non preempt kernel, the 10 second run will
 256                  * stop everything while it runs. Instead, we will call
 257                  * cond_resched and also add any time that was lost by a
 258                  * rescedule.
 259                  *
 260                  * Do a cond resched at the same frequency we would wake up
 261                  * the reader.
 262                  */
 263                 if (cnt % wakeup_interval)
 264                         cond_resched();
 265 #endif
 266
 267         } while (ktime_before(end_time, timeout) && !kill_test);
 268         trace_printk("End ring buffer hammer\n");
 269
 270         if (consumer) {
 271                 /* Init both completions here to avoid races */
 272                 init_completion(&read_start);
 273                 init_completion(&read_done);
 274                 /* the completions must be visible before the finish var */
 275                 smp_wmb();
 276                 reader_finish = 1;
 277                 /* finish var visible before waking up the consumer */
 278                 smp_wmb();
 279                 wake_up_process(consumer);
 280                 wait_for_completion(&read_done);
 281         }
 282
 283         time = ktime_us_delta(end_time, start_time);
 284
 285         entries = ring_buffer_entries(buffer);
 286         overruns = ring_buffer_overruns(buffer);
 287
 288         if (kill_test)
 289                 trace_printk("ERROR!\n");
 290
 291         if (!disable_reader) {
 292                 if (consumer_fifo < 0)
 293                         trace_printk("Running Consumer at nice: %d\n",
 294                                      consumer_nice);
 295                 else
 296                         trace_printk("Running Consumer at SCHED_FIFO %d\n",
 297                                      consumer_fifo);
 298         }
 299         if (producer_fifo < 0)
 300                 trace_printk("Running Producer at nice: %d\n",
 301                              producer_nice);
 302         else
 303                 trace_printk("Running Producer at SCHED_FIFO %d\n",
 304                              producer_fifo);
 305
 306         /* Let the user know that the test is running at low priority */
 307         if (producer_fifo < 0 && consumer_fifo < 0 &&
 308             producer_nice == MAX_NICE && consumer_nice == MAX_NICE)
 309                 trace_printk("WARNING!!! This test is running at lowest priority.\n");
 310
 311         trace_printk("Time:     %lld (usecs)\n", time);
 312         trace_printk("Overruns: %lld\n", overruns);
 313         if (disable_reader)
 314                 trace_printk("Read:     (reader disabled)\n");
 315         else
 316                 trace_printk("Read:     %ld  (by %s)\n", read,
 317                         read_events ? "events" : "pages");
 318         trace_printk("Entries:  %lld\n", entries);
 319         trace_printk("Total:    %lld\n", entries + overruns + read);
 320         trace_printk("Missed:   %ld\n", missed);
 321         trace_printk("Hit:      %ld\n", hit);
 322
 323         /* Convert time from usecs to millisecs */
 324         do_div(time, USEC_PER_MSEC);
 325         if (time)
 326                 hit /= (long)time;
 327         else
 328                 trace_printk("TIME IS ZERO??\n");
 329
 330         trace_printk("Entries per millisec: %ld\n", hit);
 331
 332         if (hit) {
 333                 /* Calculate the average time in nanosecs */
 334                 avg = NSEC_PER_MSEC / hit;
 335                 trace_printk("%ld ns per entry\n", avg);
 336         }
 337
 338         if (missed) {
 339                 if (time)
 340                         missed /= (long)time;
 341
 342                 trace_printk("Total iterations per millisec: %ld\n",
 343                              hit + missed);
 344
 345                 /* it is possible that hit + missed will overflow and be zero */
 346                 if (!(hit + missed)) {
 347                         trace_printk("hit + missed overflowed and totalled zero!\n");
 348                         hit--; /* make it non zero */
 349                 }
 350
 351                 /* Caculate the average time in nanosecs */
 352                 avg = NSEC_PER_MSEC / (hit + missed);
 353                 trace_printk("%ld ns per entry\n", avg);
 354         }
 355 }
 356
 357 static void wait_to_die(void)
 358 {
 359         set_current_state(TASK_INTERRUPTIBLE);
 360         while (!kthread_should_stop()) {
 361                 schedule();
 362                 set_current_state(TASK_INTERRUPTIBLE);
 363         }
 364         __set_current_state(TASK_RUNNING);
 365 }
 366
 367 static int ring_buffer_consumer_thread(void *arg)
 368 {
 369         while (!kthread_should_stop() && !kill_test) {
 370                 complete(&read_start);
 371
 372                 ring_buffer_consumer();
 373
 374                 set_current_state(TASK_INTERRUPTIBLE);
 375                 if (kthread_should_stop() || kill_test)
 376                         break;
 377
 378                 schedule();
 379         }
 380         __set_current_state(TASK_RUNNING);
 381
 382         if (kill_test)
 383                 wait_to_die();
 384
 385         return 0;
 386 }
 387
 388 static int ring_buffer_producer_thread(void *arg)
 389 {
 390         init_completion(&read_start);
 391
 392         while (!kthread_should_stop() && !kill_test) {
 393                 ring_buffer_reset(buffer);
 394
 395                 if (consumer) {
 396                         smp_wmb();
 397                         wake_up_process(consumer);
 398                         wait_for_completion(&read_start);
 399                 }
 400
 401                 ring_buffer_producer();
 402
 403                 trace_printk("Sleeping for 10 secs\n");
 404                 set_current_state(TASK_INTERRUPTIBLE);
 405                 schedule_timeout(HZ * SLEEP_TIME);
 406         }
 407
 408         if (kill_test)
 409                 wait_to_die();
 410
 411         return 0;
 412 }
 413
 414 static int __init ring_buffer_benchmark_init(void)
 415 {
 416         int ret;
 417
 418         /* make a one meg buffer in overwite mode */
 419         buffer = ring_buffer_alloc(1000000, RB_FL_OVERWRITE);
 420         if (!buffer)
 421                 return -ENOMEM;
 422
 423         if (!disable_reader) {
 424                 consumer = kthread_create(ring_buffer_consumer_thread,
 425                                           NULL, "rb_consumer");
 426                 ret = PTR_ERR(consumer);
 427                 if (IS_ERR(consumer))
 428                         goto out_fail;
 429         }
 430
 431         producer = kthread_run(ring_buffer_producer_thread,
 432                                NULL, "rb_producer");
 433         ret = PTR_ERR(producer);
 434
 435         if (IS_ERR(producer))
 436                 goto out_kill;
 437
 438         /*
 439          * Run them as low-prio background tasks by default:
 440          */
 441         if (!disable_reader) {
 442                 if (consumer_fifo >= 0) {
 443                         struct sched_param param = {
 444                                 .sched_priority = consumer_fifo
 445                         };
 446                         sched_setscheduler(consumer, SCHED_FIFO, &param);
 447                 } else
 448                         set_user_nice(consumer, consumer_nice);
 449         }
 450
 451         if (producer_fifo >= 0) {
 452                 struct sched_param param = {
 453                         .sched_priority = consumer_fifo
 454                 };
 455                 sched_setscheduler(producer, SCHED_FIFO, &param);
 456         } else
 457                 set_user_nice(producer, producer_nice);
 458
 459         return 0;
 460
 461  out_kill:
 462         if (consumer)
 463                 kthread_stop(consumer);
 464
 465  out_fail:
 466         ring_buffer_free(buffer);
 467         return ret;
 468 }
 469
 470 static void __exit ring_buffer_benchmark_exit(void)
 471 {
 472         kthread_stop(producer);
 473         if (consumer)
 474                 kthread_stop(consumer);
 475         ring_buffer_free(buffer);
 476 }
 477
 478 module_init(ring_buffer_benchmark_init);
 479 module_exit(ring_buffer_benchmark_exit);
 480
 481 MODULE_AUTHOR("Steven Rostedt");
 482 MODULE_DESCRIPTION("ring_buffer_benchmark");
 483 MODULE_LICENSE("GPL");