1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * ring buffer tester and benchmark 4 * 5 * Copyright (C) 2009 Steven Rostedt <srostedt@redhat.com> 6 */ 7 #include <linux/ring_buffer.h> 8 #include <linux/completion.h> 9 #include <linux/kthread.h> 10 #include <uapi/linux/sched/types.h> 11 #include <linux/module.h> 12 #include <linux/ktime.h> 13 #include <asm/local.h> 14 15 struct rb_page { 16 u64 ts; 17 local_t commit; 18 char data[4080]; 19 }; 20 21 /* run time and sleep time in seconds */ 22 #define RUN_TIME 10ULL 23 #define SLEEP_TIME 10 24 25 /* number of events for writer to wake up the reader */ 26 static int wakeup_interval = 100; 27 28 static int reader_finish; 29 static DECLARE_COMPLETION(read_start); 30 static DECLARE_COMPLETION(read_done); 31 32 static struct trace_buffer *buffer; 33 static struct task_struct *producer; 34 static struct task_struct *consumer; 35 static unsigned long read; 36 37 static unsigned int disable_reader; 38 module_param(disable_reader, uint, 0644); 39 MODULE_PARM_DESC(disable_reader, "only run producer"); 40 41 static unsigned int write_iteration = 50; 42 module_param(write_iteration, uint, 0644); 43 MODULE_PARM_DESC(write_iteration, "# of writes between timestamp readings"); 44 45 static int producer_nice = MAX_NICE; 46 static int consumer_nice = MAX_NICE; 47 48 static int producer_fifo; 49 static int consumer_fifo; 50 51 module_param(producer_nice, int, 0644); 52 MODULE_PARM_DESC(producer_nice, "nice prio for producer"); 53 54 module_param(consumer_nice, int, 0644); 55 MODULE_PARM_DESC(consumer_nice, "nice prio for consumer"); 56 57 module_param(producer_fifo, int, 0644); 58 MODULE_PARM_DESC(producer_fifo, "use fifo for producer: 0 - disabled, 1 - low prio, 2 - fifo"); 59 60 module_param(consumer_fifo, int, 0644); 61 MODULE_PARM_DESC(consumer_fifo, "use fifo for consumer: 0 - disabled, 1 - low prio, 2 - fifo"); 62 63 static int read_events; 64 65 static int test_error; 66 67 #define TEST_ERROR() \ 68 do { \ 69 if (!test_error) { \ 70 test_error = 1; \ 71 WARN_ON(1); \ 72 } \ 73 } while (0) 74 75 enum event_status { 76 EVENT_FOUND, 77 EVENT_DROPPED, 78 }; 79 80 static bool break_test(void) 81 { 82 return test_error || kthread_should_stop(); 83 } 84 85 static enum event_status read_event(int cpu) 86 { 87 struct ring_buffer_event *event; 88 int *entry; 89 u64 ts; 90 91 event = ring_buffer_consume(buffer, cpu, &ts, NULL); 92 if (!event) 93 return EVENT_DROPPED; 94 95 entry = ring_buffer_event_data(event); 96 if (*entry != cpu) { 97 TEST_ERROR(); 98 return EVENT_DROPPED; 99 } 100 101 read++; 102 return EVENT_FOUND; 103 } 104 105 static enum event_status read_page(int cpu) 106 { 107 struct buffer_data_read_page *bpage; 108 struct ring_buffer_event *event; 109 struct rb_page *rpage; 110 unsigned long commit; 111 int page_size; 112 int *entry; 113 int ret; 114 int inc; 115 int i; 116 117 bpage = ring_buffer_alloc_read_page(buffer, cpu); 118 if (IS_ERR(bpage)) 119 return EVENT_DROPPED; 120 121 page_size = ring_buffer_subbuf_size_get(buffer); 122 ret = ring_buffer_read_page(buffer, bpage, page_size, cpu, 1); 123 if (ret >= 0) { 124 rpage = ring_buffer_read_page_data(bpage); 125 /* The commit may have missed event flags set, clear them */ 126 commit = local_read(&rpage->commit) & 0xfffff; 127 for (i = 0; i < commit && !test_error ; i += inc) { 128 129 if (i >= (page_size - offsetof(struct rb_page, data))) { 130 TEST_ERROR(); 131 break; 132 } 133 134 inc = -1; 135 event = (void *)&rpage->data[i]; 136 switch (event->type_len) { 137 case RINGBUF_TYPE_PADDING: 138 /* failed writes may be discarded events */ 139 if (!event->time_delta) 140 TEST_ERROR(); 141 inc = event->array[0] + 4; 142 break; 143 case RINGBUF_TYPE_TIME_EXTEND: 144 inc = 8; 145 break; 146 case 0: 147 entry = ring_buffer_event_data(event); 148 if (*entry != cpu) { 149 TEST_ERROR(); 150 break; 151 } 152 read++; 153 if (!event->array[0]) { 154 TEST_ERROR(); 155 break; 156 } 157 inc = event->array[0] + 4; 158 break; 159 default: 160 entry = ring_buffer_event_data(event); 161 if (*entry != cpu) { 162 TEST_ERROR(); 163 break; 164 } 165 read++; 166 inc = ((event->type_len + 1) * 4); 167 } 168 if (test_error) 169 break; 170 171 if (inc <= 0) { 172 TEST_ERROR(); 173 break; 174 } 175 } 176 } 177 ring_buffer_free_read_page(buffer, cpu, bpage); 178 179 if (ret < 0) 180 return EVENT_DROPPED; 181 return EVENT_FOUND; 182 } 183 184 static void ring_buffer_consumer(void) 185 { 186 /* toggle between reading pages and events */ 187 read_events ^= 1; 188 189 read = 0; 190 /* 191 * Continue running until the producer specifically asks to stop 192 * and is ready for the completion. 193 */ 194 while (!READ_ONCE(reader_finish)) { 195 int found = 1; 196 197 while (found && !test_error) { 198 int cpu; 199 200 found = 0; 201 for_each_online_cpu(cpu) { 202 enum event_status stat; 203 204 if (read_events) 205 stat = read_event(cpu); 206 else 207 stat = read_page(cpu); 208 209 if (test_error) 210 break; 211 212 if (stat == EVENT_FOUND) 213 found = 1; 214 215 } 216 } 217 218 /* Wait till the producer wakes us up when there is more data 219 * available or when the producer wants us to finish reading. 220 */ 221 set_current_state(TASK_INTERRUPTIBLE); 222 if (reader_finish) 223 break; 224 225 schedule(); 226 } 227 __set_current_state(TASK_RUNNING); 228 reader_finish = 0; 229 complete(&read_done); 230 } 231 232 static void ring_buffer_producer(void) 233 { 234 ktime_t start_time, end_time, timeout; 235 unsigned long long time; 236 unsigned long long entries; 237 unsigned long long overruns; 238 unsigned long missed = 0; 239 unsigned long hit = 0; 240 unsigned long avg; 241 int cnt = 0; 242 243 /* 244 * Hammer the buffer for 10 secs (this may 245 * make the system stall) 246 */ 247 trace_printk("Starting ring buffer hammer\n"); 248 start_time = ktime_get(); 249 timeout = ktime_add_ns(start_time, RUN_TIME * NSEC_PER_SEC); 250 do { 251 struct ring_buffer_event *event; 252 int *entry; 253 int i; 254 255 for (i = 0; i < write_iteration; i++) { 256 event = ring_buffer_lock_reserve(buffer, 10); 257 if (!event) { 258 missed++; 259 } else { 260 hit++; 261 entry = ring_buffer_event_data(event); 262 *entry = smp_processor_id(); 263 ring_buffer_unlock_commit(buffer); 264 } 265 } 266 end_time = ktime_get(); 267 268 cnt++; 269 if (consumer && !(cnt % wakeup_interval)) 270 wake_up_process(consumer); 271 272 #ifndef CONFIG_PREEMPTION 273 /* 274 * If we are a non preempt kernel, the 10 seconds run will 275 * stop everything while it runs. Instead, we will call 276 * cond_resched and also add any time that was lost by a 277 * reschedule. 278 * 279 * Do a cond resched at the same frequency we would wake up 280 * the reader. 281 */ 282 if (cnt % wakeup_interval) 283 cond_resched(); 284 #endif 285 } while (ktime_before(end_time, timeout) && !break_test()); 286 trace_printk("End ring buffer hammer\n"); 287 288 if (consumer) { 289 /* Init both completions here to avoid races */ 290 init_completion(&read_start); 291 init_completion(&read_done); 292 /* the completions must be visible before the finish var */ 293 smp_wmb(); 294 reader_finish = 1; 295 wake_up_process(consumer); 296 wait_for_completion(&read_done); 297 } 298 299 time = ktime_us_delta(end_time, start_time); 300 301 entries = ring_buffer_entries(buffer); 302 overruns = ring_buffer_overruns(buffer); 303 304 if (test_error) 305 trace_printk("ERROR!\n"); 306 307 if (!disable_reader) { 308 if (consumer_fifo) 309 trace_printk("Running Consumer at SCHED_FIFO %s\n", 310 consumer_fifo == 1 ? "low" : "high"); 311 else 312 trace_printk("Running Consumer at nice: %d\n", 313 consumer_nice); 314 } 315 if (producer_fifo) 316 trace_printk("Running Producer at SCHED_FIFO %s\n", 317 producer_fifo == 1 ? "low" : "high"); 318 else 319 trace_printk("Running Producer at nice: %d\n", 320 producer_nice); 321 322 /* Let the user know that the test is running at low priority */ 323 if (!producer_fifo && !consumer_fifo && 324 producer_nice == MAX_NICE && consumer_nice == MAX_NICE) 325 trace_printk("WARNING!!! This test is running at lowest priority.\n"); 326 327 trace_printk("Time: %lld (usecs)\n", time); 328 trace_printk("Overruns: %lld\n", overruns); 329 if (disable_reader) 330 trace_printk("Read: (reader disabled)\n"); 331 else 332 trace_printk("Read: %ld (by %s)\n", read, 333 read_events ? "events" : "pages"); 334 trace_printk("Entries: %lld\n", entries); 335 trace_printk("Total: %lld\n", entries + overruns + read); 336 trace_printk("Missed: %ld\n", missed); 337 trace_printk("Hit: %ld\n", hit); 338 339 /* Convert time from usecs to millisecs */ 340 do_div(time, USEC_PER_MSEC); 341 if (time) 342 hit /= (long)time; 343 else 344 trace_printk("TIME IS ZERO??\n"); 345 346 trace_printk("Entries per millisec: %ld\n", hit); 347 348 if (hit) { 349 /* Calculate the average time in nanosecs */ 350 avg = NSEC_PER_MSEC / hit; 351 trace_printk("%ld ns per entry\n", avg); 352 } 353 354 if (missed) { 355 if (time) 356 missed /= (long)time; 357 358 trace_printk("Total iterations per millisec: %ld\n", 359 hit + missed); 360 361 /* it is possible that hit + missed will overflow and be zero */ 362 if (!(hit + missed)) { 363 trace_printk("hit + missed overflowed and totalled zero!\n"); 364 hit--; /* make it non zero */ 365 } 366 367 /* Calculate the average time in nanosecs */ 368 avg = NSEC_PER_MSEC / (hit + missed); 369 trace_printk("%ld ns per entry\n", avg); 370 } 371 } 372 373 static void wait_to_die(void) 374 { 375 set_current_state(TASK_INTERRUPTIBLE); 376 while (!kthread_should_stop()) { 377 schedule(); 378 set_current_state(TASK_INTERRUPTIBLE); 379 } 380 __set_current_state(TASK_RUNNING); 381 } 382 383 static int ring_buffer_consumer_thread(void *arg) 384 { 385 while (!break_test()) { 386 complete(&read_start); 387 388 ring_buffer_consumer(); 389 390 set_current_state(TASK_INTERRUPTIBLE); 391 if (break_test()) 392 break; 393 schedule(); 394 } 395 __set_current_state(TASK_RUNNING); 396 397 if (!kthread_should_stop()) 398 wait_to_die(); 399 400 return 0; 401 } 402 403 static int ring_buffer_producer_thread(void *arg) 404 { 405 while (!break_test()) { 406 ring_buffer_reset(buffer); 407 408 if (consumer) { 409 wake_up_process(consumer); 410 wait_for_completion(&read_start); 411 } 412 413 ring_buffer_producer(); 414 if (break_test()) 415 goto out_kill; 416 417 trace_printk("Sleeping for 10 secs\n"); 418 set_current_state(TASK_INTERRUPTIBLE); 419 if (break_test()) 420 goto out_kill; 421 schedule_timeout(HZ * SLEEP_TIME); 422 } 423 424 out_kill: 425 __set_current_state(TASK_RUNNING); 426 if (!kthread_should_stop()) 427 wait_to_die(); 428 429 return 0; 430 } 431 432 static int __init ring_buffer_benchmark_init(void) 433 { 434 int ret; 435 436 /* make a one meg buffer in overwite mode */ 437 buffer = ring_buffer_alloc(1000000, RB_FL_OVERWRITE); 438 if (!buffer) 439 return -ENOMEM; 440 441 if (!disable_reader) { 442 consumer = kthread_create(ring_buffer_consumer_thread, 443 NULL, "rb_consumer"); 444 ret = PTR_ERR(consumer); 445 if (IS_ERR(consumer)) 446 goto out_fail; 447 } 448 449 producer = kthread_run(ring_buffer_producer_thread, 450 NULL, "rb_producer"); 451 ret = PTR_ERR(producer); 452 453 if (IS_ERR(producer)) 454 goto out_kill; 455 456 /* 457 * Run them as low-prio background tasks by default: 458 */ 459 if (!disable_reader) { 460 if (consumer_fifo >= 2) 461 sched_set_fifo(consumer); 462 else if (consumer_fifo == 1) 463 sched_set_fifo_low(consumer); 464 else 465 set_user_nice(consumer, consumer_nice); 466 } 467 468 if (producer_fifo >= 2) 469 sched_set_fifo(producer); 470 else if (producer_fifo == 1) 471 sched_set_fifo_low(producer); 472 else 473 set_user_nice(producer, producer_nice); 474 475 return 0; 476 477 out_kill: 478 if (consumer) 479 kthread_stop(consumer); 480 481 out_fail: 482 ring_buffer_free(buffer); 483 return ret; 484 } 485 486 static void __exit ring_buffer_benchmark_exit(void) 487 { 488 kthread_stop(producer); 489 if (consumer) 490 kthread_stop(consumer); 491 ring_buffer_free(buffer); 492 } 493 494 module_init(ring_buffer_benchmark_init); 495 module_exit(ring_buffer_benchmark_exit); 496 497 MODULE_AUTHOR("Steven Rostedt"); 498 MODULE_DESCRIPTION("ring_buffer_benchmark"); 499 MODULE_LICENSE("GPL"); 500