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                 cnt++;
 222                 if (consumer && !(cnt % wakeup_interval))
 223                         wake_up_process(consumer);
 224
 225 #ifndef CONFIG_PREEMPT
 226                 /*
 227                  * If we are a non preempt kernel, the 10 second run will
 228                  * stop everything while it runs. Instead, we will call
 229                  * cond_resched and also add any time that was lost by a
 230                  * rescedule.
 231                  *
 232                  * Do a cond resched at the same frequency we would wake up
 233                  * the reader.
 234                  */
 235                 if (cnt % wakeup_interval)
 236                         cond_resched();
 237 #endif
 238
 239         } while (end_tv.tv_sec < (start_tv.tv_sec + RUN_TIME) && !kill_test);
 240         pr_info("End ring buffer hammer\n");
 241
 242         if (consumer) {
 243                 /* Init both completions here to avoid races */
 244                 init_completion(&read_start);
 245                 init_completion(&read_done);
 246                 /* the completions must be visible before the finish var */
 247                 smp_wmb();
 248                 reader_finish = 1;
 249                 /* finish var visible before waking up the consumer */
 250                 smp_wmb();
 251                 wake_up_process(consumer);
 252                 wait_for_completion(&read_done);
 253         }
 254
 255         time = end_tv.tv_sec - start_tv.tv_sec;
 256         time *= USEC_PER_SEC;
 257         time += (long long)((long)end_tv.tv_usec - (long)start_tv.tv_usec);
 258
 259         entries = ring_buffer_entries(buffer);
 260         overruns = ring_buffer_overruns(buffer);
 261
 262         if (kill_test)
 263                 pr_info("ERROR!\n");
 264         pr_info("Time:     %lld (usecs)\n", time);
 265         pr_info("Overruns: %lld\n", overruns);
 266         if (disable_reader)
 267                 pr_info("Read:     (reader disabled)\n");
 268         else
 269                 pr_info("Read:     %ld  (by %s)\n", read,
 270                         read_events ? "events" : "pages");
 271         pr_info("Entries:  %lld\n", entries);
 272         pr_info("Total:    %lld\n", entries + overruns + read);
 273         pr_info("Missed:   %ld\n", missed);
 274         pr_info("Hit:      %ld\n", hit);
 275
 276         /* Convert time from usecs to millisecs */
 277         do_div(time, USEC_PER_MSEC);
 278         if (time)
 279                 hit /= (long)time;
 280         else
 281                 pr_info("TIME IS ZERO??\n");
 282
 283         pr_info("Entries per millisec: %ld\n", hit);
 284
 285         if (hit) {
 286                 /* Calculate the average time in nanosecs */
 287                 avg = NSEC_PER_MSEC / hit;
 288                 pr_info("%ld ns per entry\n", avg);
 289         }
 290
 291         if (missed) {
 292                 if (time)
 293                         missed /= (long)time;
 294
 295                 pr_info("Total iterations per millisec: %ld\n", hit + missed);
 296
 297                 /* it is possible that hit + missed will overflow and be zero */
 298                 if (!(hit + missed)) {
 299                         pr_info("hit + missed overflowed and totalled zero!\n");
 300                         hit--; /* make it non zero */
 301                 }
 302
 303                 /* Caculate the average time in nanosecs */
 304                 avg = NSEC_PER_MSEC / (hit + missed);
 305                 pr_info("%ld ns per entry\n", avg);
 306         }
 307 }
 308
 309 static void wait_to_die(void)
 310 {
 311         set_current_state(TASK_INTERRUPTIBLE);
 312         while (!kthread_should_stop()) {
 313                 schedule();
 314                 set_current_state(TASK_INTERRUPTIBLE);
 315         }
 316         __set_current_state(TASK_RUNNING);
 317 }
 318
 319 static int ring_buffer_consumer_thread(void *arg)
 320 {
 321         while (!kthread_should_stop() && !kill_test) {
 322                 complete(&read_start);
 323
 324                 ring_buffer_consumer();
 325
 326                 set_current_state(TASK_INTERRUPTIBLE);
 327                 if (kthread_should_stop() || kill_test)
 328                         break;
 329
 330                 schedule();
 331                 __set_current_state(TASK_RUNNING);
 332         }
 333         __set_current_state(TASK_RUNNING);
 334
 335         if (kill_test)
 336                 wait_to_die();
 337
 338         return 0;
 339 }
 340
 341 static int ring_buffer_producer_thread(void *arg)
 342 {
 343         init_completion(&read_start);
 344
 345         while (!kthread_should_stop() && !kill_test) {
 346                 ring_buffer_reset(buffer);
 347
 348                 if (consumer) {
 349                         smp_wmb();
 350                         wake_up_process(consumer);
 351                         wait_for_completion(&read_start);
 352                 }
 353
 354                 ring_buffer_producer();
 355
 356                 pr_info("Sleeping for 10 secs\n");
 357                 set_current_state(TASK_INTERRUPTIBLE);
 358                 schedule_timeout(HZ * SLEEP_TIME);
 359                 __set_current_state(TASK_RUNNING);
 360         }
 361
 362         if (kill_test)
 363                 wait_to_die();
 364
 365         return 0;
 366 }
 367
 368 static int __init ring_buffer_benchmark_init(void)
 369 {
 370         int ret;
 371
 372         /* make a one meg buffer in overwite mode */
 373         buffer = ring_buffer_alloc(1000000, RB_FL_OVERWRITE);
 374         if (!buffer)
 375                 return -ENOMEM;
 376
 377         if (!disable_reader) {
 378                 consumer = kthread_create(ring_buffer_consumer_thread,
 379                                           NULL, "rb_consumer");
 380                 ret = PTR_ERR(consumer);
 381                 if (IS_ERR(consumer))
 382                         goto out_fail;
 383         }
 384
 385         producer = kthread_run(ring_buffer_producer_thread,
 386                                NULL, "rb_producer");
 387         ret = PTR_ERR(producer);
 388
 389         if (IS_ERR(producer))
 390                 goto out_kill;
 391
 392         return 0;
 393
 394  out_kill:
 395         if (consumer)
 396                 kthread_stop(consumer);
 397
 398  out_fail:
 399         ring_buffer_free(buffer);
 400         return ret;
 401 }
 402
 403 static void __exit ring_buffer_benchmark_exit(void)
 404 {
 405         kthread_stop(producer);
 406         if (consumer)
 407                 kthread_stop(consumer);
 408         ring_buffer_free(buffer);
 409 }
 410
 411 module_init(ring_buffer_benchmark_init);
 412 module_exit(ring_buffer_benchmark_exit);
 413
 414 MODULE_AUTHOR("Steven Rostedt");
 415 MODULE_DESCRIPTION("ring_buffer_benchmark");
 416 MODULE_LICENSE("GPL");