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Steven Rostedt5092dbc2009-05-05 22:47:18 -04001/*
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>
Christoph Lameter79615762010-01-05 15:34:50 +090011#include <asm/local.h>
Steven Rostedt5092dbc2009-05-05 22:47:18 -040012
13struct 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 */
24static int wakeup_interval = 100;
25
26static int reader_finish;
27static struct completion read_start;
28static struct completion read_done;
29
30static struct ring_buffer *buffer;
31static struct task_struct *producer;
32static struct task_struct *consumer;
33static unsigned long read;
34
35static int disable_reader;
36module_param(disable_reader, uint, 0644);
37MODULE_PARM_DESC(disable_reader, "only run producer");
38
Steven Rostedta6f0eb62009-11-11 17:14:07 -050039static int write_iteration = 50;
40module_param(write_iteration, uint, 0644);
41MODULE_PARM_DESC(write_iteration, "# of writes between timestamp readings");
42
Steven Rostedt7ac07432009-11-25 13:22:21 -050043static int producer_nice = 19;
44static int consumer_nice = 19;
45
46static int producer_fifo = -1;
47static int consumer_fifo = -1;
48
49module_param(producer_nice, uint, 0644);
50MODULE_PARM_DESC(producer_nice, "nice prio for producer");
51
52module_param(consumer_nice, uint, 0644);
53MODULE_PARM_DESC(consumer_nice, "nice prio for consumer");
54
55module_param(producer_fifo, uint, 0644);
56MODULE_PARM_DESC(producer_fifo, "fifo prio for producer");
57
58module_param(consumer_fifo, uint, 0644);
59MODULE_PARM_DESC(consumer_fifo, "fifo prio for consumer");
60
Steven Rostedt5092dbc2009-05-05 22:47:18 -040061static int read_events;
62
63static 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
73enum event_status {
74 EVENT_FOUND,
75 EVENT_DROPPED,
76};
77
78static enum event_status read_event(int cpu)
79{
80 struct ring_buffer_event *event;
81 int *entry;
82 u64 ts;
83
Steven Rostedt66a8cb92010-03-31 13:21:56 -040084 event = ring_buffer_consume(buffer, cpu, &ts, NULL);
Steven Rostedt5092dbc2009-05-05 22:47:18 -040085 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
98static 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
Vaibhav Nagarnaik7ea59062011-05-03 17:56:42 -0700109 bpage = ring_buffer_alloc_read_page(buffer, cpu);
Steven Rostedt00c81a52009-05-06 12:40:51 -0400110 if (!bpage)
111 return EVENT_DROPPED;
112
Steven Rostedt5092dbc2009-05-05 22:47:18 -0400113 ret = ring_buffer_read_page(buffer, &bpage, PAGE_SIZE, cpu, 1);
114 if (ret >= 0) {
115 rpage = bpage;
Steven Rostedta838b2e2010-04-27 13:26:58 -0400116 /* The commit may have missed event flags set, clear them */
117 commit = local_read(&rpage->commit) & 0xfffff;
Steven Rostedt5092dbc2009-05-05 22:47:18 -0400118 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:
Steven Rostedt9086c7b902009-06-16 11:46:09 -0400129 /* failed writes may be discarded events */
130 if (!event->time_delta)
131 KILL_TEST();
132 inc = event->array[0] + 4;
Steven Rostedt5092dbc2009-05-05 22:47:18 -0400133 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 }
Steven Rostedt9086c7b902009-06-16 11:46:09 -0400148 inc = event->array[0] + 4;
Steven Rostedt5092dbc2009-05-05 22:47:18 -0400149 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
175static 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
214static 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 */
Steven Rostedt4b221f02009-06-17 17:01:09 -0400230 trace_printk("Starting ring buffer hammer\n");
Steven Rostedt5092dbc2009-05-05 22:47:18 -0400231 do_gettimeofday(&start_tv);
232 do {
233 struct ring_buffer_event *event;
234 int *entry;
Steven Rostedta6f0eb62009-11-11 17:14:07 -0500235 int i;
Steven Rostedt5092dbc2009-05-05 22:47:18 -0400236
Steven Rostedta6f0eb62009-11-11 17:14:07 -0500237 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 }
Steven Rostedt5092dbc2009-05-05 22:47:18 -0400247 }
248 do_gettimeofday(&end_tv);
249
Steven Rostedt0574ea42009-05-07 14:20:28 -0400250 cnt++;
251 if (consumer && !(cnt % wakeup_interval))
Steven Rostedt5092dbc2009-05-05 22:47:18 -0400252 wake_up_process(consumer);
253
Steven Rostedt0574ea42009-05-07 14:20:28 -0400254#ifndef CONFIG_PREEMPT
Steven Rostedt29c80002009-05-07 11:13:42 -0400255 /*
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.
Steven Rostedt0574ea42009-05-07 14:20:28 -0400260 *
261 * Do a cond resched at the same frequency we would wake up
262 * the reader.
Steven Rostedt29c80002009-05-07 11:13:42 -0400263 */
Steven Rostedt0574ea42009-05-07 14:20:28 -0400264 if (cnt % wakeup_interval)
265 cond_resched();
266#endif
Steven Rostedt3e07a4f2009-05-06 18:36:59 -0400267
Steven Rostedt5092dbc2009-05-05 22:47:18 -0400268 } while (end_tv.tv_sec < (start_tv.tv_sec + RUN_TIME) && !kill_test);
Steven Rostedt4b221f02009-06-17 17:01:09 -0400269 trace_printk("End ring buffer hammer\n");
Steven Rostedt5092dbc2009-05-05 22:47:18 -0400270
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;
Steven Rostedt5a772b22009-05-08 10:56:33 -0400285 time *= USEC_PER_SEC;
Steven Rostedt5092dbc2009-05-05 22:47:18 -0400286 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)
Steven Rostedt4b221f02009-06-17 17:01:09 -0400292 trace_printk("ERROR!\n");
Steven Rostedt7ac07432009-11-25 13:22:21 -0500293
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
Steven Rostedt4b221f02009-06-17 17:01:09 -0400314 trace_printk("Time: %lld (usecs)\n", time);
315 trace_printk("Overruns: %lld\n", overruns);
Steven Rostedt5092dbc2009-05-05 22:47:18 -0400316 if (disable_reader)
Steven Rostedt4b221f02009-06-17 17:01:09 -0400317 trace_printk("Read: (reader disabled)\n");
Steven Rostedt5092dbc2009-05-05 22:47:18 -0400318 else
Steven Rostedt4b221f02009-06-17 17:01:09 -0400319 trace_printk("Read: %ld (by %s)\n", read,
Steven Rostedt5092dbc2009-05-05 22:47:18 -0400320 read_events ? "events" : "pages");
Steven Rostedt4b221f02009-06-17 17:01:09 -0400321 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);
Steven Rostedt5092dbc2009-05-05 22:47:18 -0400325
Steven Rostedt5a772b22009-05-08 10:56:33 -0400326 /* Convert time from usecs to millisecs */
327 do_div(time, USEC_PER_MSEC);
Steven Rostedt5092dbc2009-05-05 22:47:18 -0400328 if (time)
329 hit /= (long)time;
330 else
Steven Rostedt4b221f02009-06-17 17:01:09 -0400331 trace_printk("TIME IS ZERO??\n");
Steven Rostedt5092dbc2009-05-05 22:47:18 -0400332
Steven Rostedt4b221f02009-06-17 17:01:09 -0400333 trace_printk("Entries per millisec: %ld\n", hit);
Steven Rostedt5092dbc2009-05-05 22:47:18 -0400334
335 if (hit) {
Steven Rostedt5a772b22009-05-08 10:56:33 -0400336 /* Calculate the average time in nanosecs */
337 avg = NSEC_PER_MSEC / hit;
Steven Rostedt4b221f02009-06-17 17:01:09 -0400338 trace_printk("%ld ns per entry\n", avg);
Steven Rostedt5092dbc2009-05-05 22:47:18 -0400339 }
Steven Rostedt7da30462009-05-07 19:52:20 -0400340
Steven Rostedt7da30462009-05-07 19:52:20 -0400341 if (missed) {
342 if (time)
343 missed /= (long)time;
344
Steven Rostedt4b221f02009-06-17 17:01:09 -0400345 trace_printk("Total iterations per millisec: %ld\n",
346 hit + missed);
Steven Rostedt7da30462009-05-07 19:52:20 -0400347
Steven Rostedtd988ff92009-05-08 11:03:57 -0400348 /* it is possible that hit + missed will overflow and be zero */
349 if (!(hit + missed)) {
Steven Rostedt4b221f02009-06-17 17:01:09 -0400350 trace_printk("hit + missed overflowed and totalled zero!\n");
Steven Rostedtd988ff92009-05-08 11:03:57 -0400351 hit--; /* make it non zero */
352 }
353
Steven Rostedt5a772b22009-05-08 10:56:33 -0400354 /* Caculate the average time in nanosecs */
355 avg = NSEC_PER_MSEC / (hit + missed);
Steven Rostedt4b221f02009-06-17 17:01:09 -0400356 trace_printk("%ld ns per entry\n", avg);
Steven Rostedt7da30462009-05-07 19:52:20 -0400357 }
Steven Rostedt5092dbc2009-05-05 22:47:18 -0400358}
359
360static 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
370static 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
392static 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
Steven Rostedt4b221f02009-06-17 17:01:09 -0400407 trace_printk("Sleeping for 10 secs\n");
Steven Rostedt5092dbc2009-05-05 22:47:18 -0400408 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
419static 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
Ingo Molnar98e48332009-11-23 08:03:09 +0100443 /*
444 * Run them as low-prio background tasks by default:
445 */
Steven Rostedt7ac07432009-11-25 13:22:21 -0500446 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, &param);
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, &param);
461 } else
462 set_user_nice(producer, producer_nice);
Ingo Molnar98e48332009-11-23 08:03:09 +0100463
Steven Rostedt5092dbc2009-05-05 22:47:18 -0400464 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
475static 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
483module_init(ring_buffer_benchmark_init);
484module_exit(ring_buffer_benchmark_exit);
485
486MODULE_AUTHOR("Steven Rostedt");
487MODULE_DESCRIPTION("ring_buffer_benchmark");
488MODULE_LICENSE("GPL");