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"); 417