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 #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 10
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 = 19;
44 static int consumer_nice = 19;
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
read_event(int cpu)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
read_page(int cpu)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);
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
ring_buffer_consumer(void)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 __set_current_state(TASK_RUNNING);
209 }
210 reader_finish = 0;
211 complete(&read_done);
212 }
213
ring_buffer_producer(void)214 static void ring_buffer_producer(void)
215 {
216 struct timeval start_tv;
217 struct timeval end_tv;
218 unsigned long long time;
219 unsigned long long entries;
220 unsigned long long overruns;
221 unsigned long missed = 0;
222 unsigned long hit = 0;
223 unsigned long avg;
224 int cnt = 0;
225
226 /*
227 * Hammer the buffer for 10 secs (this may
228 * make the system stall)
229 */
230 trace_printk("Starting ring buffer hammer\n");
231 do_gettimeofday(&start_tv);
232 do {
233 struct ring_buffer_event *event;
234 int *entry;
235 int i;
236
237 for (i = 0; i < write_iteration; i++) {
238 event = ring_buffer_lock_reserve(buffer, 10);
239 if (!event) {
240 missed++;
241 } else {
242 hit++;
243 entry = ring_buffer_event_data(event);
244 *entry = smp_processor_id();
245 ring_buffer_unlock_commit(buffer, event);
246 }
247 }
248 do_gettimeofday(&end_tv);
249
250 cnt++;
251 if (consumer && !(cnt % wakeup_interval))
252 wake_up_process(consumer);
253
254 #ifndef CONFIG_PREEMPT
255 /*
256 * If we are a non preempt kernel, the 10 second run will
257 * stop everything while it runs. Instead, we will call
258 * cond_resched and also add any time that was lost by a
259 * rescedule.
260 *
261 * Do a cond resched at the same frequency we would wake up
262 * the reader.
263 */
264 if (cnt % wakeup_interval)
265 cond_resched();
266 #endif
267
268 } while (end_tv.tv_sec < (start_tv.tv_sec + RUN_TIME) && !kill_test);
269 trace_printk("End ring buffer hammer\n");
270
271 if (consumer) {
272 /* Init both completions here to avoid races */
273 init_completion(&read_start);
274 init_completion(&read_done);
275 /* the completions must be visible before the finish var */
276 smp_wmb();
277 reader_finish = 1;
278 /* finish var visible before waking up the consumer */
279 smp_wmb();
280 wake_up_process(consumer);
281 wait_for_completion(&read_done);
282 }
283
284 time = end_tv.tv_sec - start_tv.tv_sec;
285 time *= USEC_PER_SEC;
286 time += (long long)((long)end_tv.tv_usec - (long)start_tv.tv_usec);
287
288 entries = ring_buffer_entries(buffer);
289 overruns = ring_buffer_overruns(buffer);
290
291 if (kill_test)
292 trace_printk("ERROR!\n");
293
294 if (!disable_reader) {
295 if (consumer_fifo < 0)
296 trace_printk("Running Consumer at nice: %d\n",
297 consumer_nice);
298 else
299 trace_printk("Running Consumer at SCHED_FIFO %d\n",
300 consumer_fifo);
301 }
302 if (producer_fifo < 0)
303 trace_printk("Running Producer at nice: %d\n",
304 producer_nice);
305 else
306 trace_printk("Running Producer at SCHED_FIFO %d\n",
307 producer_fifo);
308
309 /* Let the user know that the test is running at low priority */
310 if (producer_fifo < 0 && consumer_fifo < 0 &&
311 producer_nice == 19 && consumer_nice == 19)
312 trace_printk("WARNING!!! This test is running at lowest priority.\n");
313
314 trace_printk("Time: %lld (usecs)\n", time);
315 trace_printk("Overruns: %lld\n", overruns);
316 if (disable_reader)
317 trace_printk("Read: (reader disabled)\n");
318 else
319 trace_printk("Read: %ld (by %s)\n", read,
320 read_events ? "events" : "pages");
321 trace_printk("Entries: %lld\n", entries);
322 trace_printk("Total: %lld\n", entries + overruns + read);
323 trace_printk("Missed: %ld\n", missed);
324 trace_printk("Hit: %ld\n", hit);
325
326 /* Convert time from usecs to millisecs */
327 do_div(time, USEC_PER_MSEC);
328 if (time)
329 hit /= (long)time;
330 else
331 trace_printk("TIME IS ZERO??\n");
332
333 trace_printk("Entries per millisec: %ld\n", hit);
334
335 if (hit) {
336 /* Calculate the average time in nanosecs */
337 avg = NSEC_PER_MSEC / hit;
338 trace_printk("%ld ns per entry\n", avg);
339 }
340
341 if (missed) {
342 if (time)
343 missed /= (long)time;
344
345 trace_printk("Total iterations per millisec: %ld\n",
346 hit + missed);
347
348 /* it is possible that hit + missed will overflow and be zero */
349 if (!(hit + missed)) {
350 trace_printk("hit + missed overflowed and totalled zero!\n");
351 hit--; /* make it non zero */
352 }
353
354 /* Caculate the average time in nanosecs */
355 avg = NSEC_PER_MSEC / (hit + missed);
356 trace_printk("%ld ns per entry\n", avg);
357 }
358 }
359
wait_to_die(void)360 static void wait_to_die(void)
361 {
362 set_current_state(TASK_INTERRUPTIBLE);
363 while (!kthread_should_stop()) {
364 schedule();
365 set_current_state(TASK_INTERRUPTIBLE);
366 }
367 __set_current_state(TASK_RUNNING);
368 }
369
ring_buffer_consumer_thread(void * arg)370 static int ring_buffer_consumer_thread(void *arg)
371 {
372 while (!kthread_should_stop() && !kill_test) {
373 complete(&read_start);
374
375 ring_buffer_consumer();
376
377 set_current_state(TASK_INTERRUPTIBLE);
378 if (kthread_should_stop() || kill_test)
379 break;
380
381 schedule();
382 __set_current_state(TASK_RUNNING);
383 }
384 __set_current_state(TASK_RUNNING);
385
386 if (kill_test)
387 wait_to_die();
388
389 return 0;
390 }
391
ring_buffer_producer_thread(void * arg)392 static int ring_buffer_producer_thread(void *arg)
393 {
394 init_completion(&read_start);
395
396 while (!kthread_should_stop() && !kill_test) {
397 ring_buffer_reset(buffer);
398
399 if (consumer) {
400 smp_wmb();
401 wake_up_process(consumer);
402 wait_for_completion(&read_start);
403 }
404
405 ring_buffer_producer();
406
407 trace_printk("Sleeping for 10 secs\n");
408 set_current_state(TASK_INTERRUPTIBLE);
409 schedule_timeout(HZ * SLEEP_TIME);
410 __set_current_state(TASK_RUNNING);
411 }
412
413 if (kill_test)
414 wait_to_die();
415
416 return 0;
417 }
418
ring_buffer_benchmark_init(void)419 static int __init ring_buffer_benchmark_init(void)
420 {
421 int ret;
422
423 /* make a one meg buffer in overwite mode */
424 buffer = ring_buffer_alloc(1000000, RB_FL_OVERWRITE);
425 if (!buffer)
426 return -ENOMEM;
427
428 if (!disable_reader) {
429 consumer = kthread_create(ring_buffer_consumer_thread,
430 NULL, "rb_consumer");
431 ret = PTR_ERR(consumer);
432 if (IS_ERR(consumer))
433 goto out_fail;
434 }
435
436 producer = kthread_run(ring_buffer_producer_thread,
437 NULL, "rb_producer");
438 ret = PTR_ERR(producer);
439
440 if (IS_ERR(producer))
441 goto out_kill;
442
443 /*
444 * Run them as low-prio background tasks by default:
445 */
446 if (!disable_reader) {
447 if (consumer_fifo >= 0) {
448 struct sched_param param = {
449 .sched_priority = consumer_fifo
450 };
451 sched_setscheduler(consumer, SCHED_FIFO, ¶m);
452 } else
453 set_user_nice(consumer, consumer_nice);
454 }
455
456 if (producer_fifo >= 0) {
457 struct sched_param param = {
458 .sched_priority = consumer_fifo
459 };
460 sched_setscheduler(producer, SCHED_FIFO, ¶m);
461 } else
462 set_user_nice(producer, producer_nice);
463
464 return 0;
465
466 out_kill:
467 if (consumer)
468 kthread_stop(consumer);
469
470 out_fail:
471 ring_buffer_free(buffer);
472 return ret;
473 }
474
ring_buffer_benchmark_exit(void)475 static void __exit ring_buffer_benchmark_exit(void)
476 {
477 kthread_stop(producer);
478 if (consumer)
479 kthread_stop(consumer);
480 ring_buffer_free(buffer);
481 }
482
483 module_init(ring_buffer_benchmark_init);
484 module_exit(ring_buffer_benchmark_exit);
485
486 MODULE_AUTHOR("Steven Rostedt");
487 MODULE_DESCRIPTION("ring_buffer_benchmark");
488 MODULE_LICENSE("GPL");
489