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