2 * ring buffer tester and benchmark
4 * Copyright (C) 2009 Steven Rostedt <srostedt@redhat.com>
6 #include <linux/ring_buffer.h>
7 #include <linux/completion.h>
8 #include <linux/kthread.h>
9 #include <linux/module.h>
10 #include <linux/ktime.h>
11 #include <asm/local.h>
19 /* run time and sleep time in seconds */
20 #define RUN_TIME 10ULL
23 /* number of events for writer to wake up the reader */
24 static int wakeup_interval = 100;
26 static int reader_finish;
27 static DECLARE_COMPLETION(read_start);
28 static DECLARE_COMPLETION(read_done);
30 static struct ring_buffer *buffer;
31 static struct task_struct *producer;
32 static struct task_struct *consumer;
33 static unsigned long read;
35 static unsigned int disable_reader;
36 module_param(disable_reader, uint, 0644);
37 MODULE_PARM_DESC(disable_reader, "only run producer");
39 static unsigned int write_iteration = 50;
40 module_param(write_iteration, uint, 0644);
41 MODULE_PARM_DESC(write_iteration, "# of writes between timestamp readings");
43 static int producer_nice = MAX_NICE;
44 static int consumer_nice = MAX_NICE;
46 static int producer_fifo = -1;
47 static int consumer_fifo = -1;
49 module_param(producer_nice, int, 0644);
50 MODULE_PARM_DESC(producer_nice, "nice prio for producer");
52 module_param(consumer_nice, int, 0644);
53 MODULE_PARM_DESC(consumer_nice, "nice prio for consumer");
55 module_param(producer_fifo, int, 0644);
56 MODULE_PARM_DESC(producer_fifo, "fifo prio for producer");
58 module_param(consumer_fifo, int, 0644);
59 MODULE_PARM_DESC(consumer_fifo, "fifo prio for consumer");
61 static int read_events;
63 static int test_error;
65 #define TEST_ERROR() \
78 static bool break_test(void)
80 return test_error || kthread_should_stop();
83 static enum event_status read_event(int cpu)
85 struct ring_buffer_event *event;
89 event = ring_buffer_consume(buffer, cpu, &ts, NULL);
93 entry = ring_buffer_event_data(event);
103 static enum event_status read_page(int cpu)
105 struct ring_buffer_event *event;
106 struct rb_page *rpage;
107 unsigned long commit;
114 bpage = ring_buffer_alloc_read_page(buffer, cpu);
116 return EVENT_DROPPED;
118 ret = ring_buffer_read_page(buffer, &bpage, PAGE_SIZE, cpu, 1);
121 /* The commit may have missed event flags set, clear them */
122 commit = local_read(&rpage->commit) & 0xfffff;
123 for (i = 0; i < commit && !test_error ; i += inc) {
125 if (i >= (PAGE_SIZE - offsetof(struct rb_page, data))) {
131 event = (void *)&rpage->data[i];
132 switch (event->type_len) {
133 case RINGBUF_TYPE_PADDING:
134 /* failed writes may be discarded events */
135 if (!event->time_delta)
137 inc = event->array[0] + 4;
139 case RINGBUF_TYPE_TIME_EXTEND:
143 entry = ring_buffer_event_data(event);
149 if (!event->array[0]) {
153 inc = event->array[0] + 4;
156 entry = ring_buffer_event_data(event);
162 inc = ((event->type_len + 1) * 4);
173 ring_buffer_free_read_page(buffer, bpage);
176 return EVENT_DROPPED;
180 static void ring_buffer_consumer(void)
182 /* toggle between reading pages and events */
187 * Continue running until the producer specifically asks to stop
188 * and is ready for the completion.
190 while (!READ_ONCE(reader_finish)) {
193 while (found && !test_error) {
197 for_each_online_cpu(cpu) {
198 enum event_status stat;
201 stat = read_event(cpu);
203 stat = read_page(cpu);
208 if (stat == EVENT_FOUND)
214 /* Wait till the producer wakes us up when there is more data
215 * available or when the producer wants us to finish reading.
217 set_current_state(TASK_INTERRUPTIBLE);
223 __set_current_state(TASK_RUNNING);
225 complete(&read_done);
228 static void ring_buffer_producer(void)
230 ktime_t start_time, end_time, timeout;
231 unsigned long long time;
232 unsigned long long entries;
233 unsigned long long overruns;
234 unsigned long missed = 0;
235 unsigned long hit = 0;
240 * Hammer the buffer for 10 secs (this may
241 * make the system stall)
243 trace_printk("Starting ring buffer hammer\n");
244 start_time = ktime_get();
245 timeout = ktime_add_ns(start_time, RUN_TIME * NSEC_PER_SEC);
247 struct ring_buffer_event *event;
251 for (i = 0; i < write_iteration; i++) {
252 event = ring_buffer_lock_reserve(buffer, 10);
257 entry = ring_buffer_event_data(event);
258 *entry = smp_processor_id();
259 ring_buffer_unlock_commit(buffer, event);
262 end_time = ktime_get();
265 if (consumer && !(cnt % wakeup_interval))
266 wake_up_process(consumer);
268 #ifndef CONFIG_PREEMPT
270 * If we are a non preempt kernel, the 10 second run will
271 * stop everything while it runs. Instead, we will call
272 * cond_resched and also add any time that was lost by a
275 * Do a cond resched at the same frequency we would wake up
278 if (cnt % wakeup_interval)
281 } while (ktime_before(end_time, timeout) && !break_test());
282 trace_printk("End ring buffer hammer\n");
285 /* Init both completions here to avoid races */
286 init_completion(&read_start);
287 init_completion(&read_done);
288 /* the completions must be visible before the finish var */
291 /* finish var visible before waking up the consumer */
293 wake_up_process(consumer);
294 wait_for_completion(&read_done);
297 time = ktime_us_delta(end_time, start_time);
299 entries = ring_buffer_entries(buffer);
300 overruns = ring_buffer_overruns(buffer);
303 trace_printk("ERROR!\n");
305 if (!disable_reader) {
306 if (consumer_fifo < 0)
307 trace_printk("Running Consumer at nice: %d\n",
310 trace_printk("Running Consumer at SCHED_FIFO %d\n",
313 if (producer_fifo < 0)
314 trace_printk("Running Producer at nice: %d\n",
317 trace_printk("Running Producer at SCHED_FIFO %d\n",
320 /* Let the user know that the test is running at low priority */
321 if (producer_fifo < 0 && consumer_fifo < 0 &&
322 producer_nice == MAX_NICE && consumer_nice == MAX_NICE)
323 trace_printk("WARNING!!! This test is running at lowest priority.\n");
325 trace_printk("Time: %lld (usecs)\n", time);
326 trace_printk("Overruns: %lld\n", overruns);
328 trace_printk("Read: (reader disabled)\n");
330 trace_printk("Read: %ld (by %s)\n", read,
331 read_events ? "events" : "pages");
332 trace_printk("Entries: %lld\n", entries);
333 trace_printk("Total: %lld\n", entries + overruns + read);
334 trace_printk("Missed: %ld\n", missed);
335 trace_printk("Hit: %ld\n", hit);
337 /* Convert time from usecs to millisecs */
338 do_div(time, USEC_PER_MSEC);
342 trace_printk("TIME IS ZERO??\n");
344 trace_printk("Entries per millisec: %ld\n", hit);
347 /* Calculate the average time in nanosecs */
348 avg = NSEC_PER_MSEC / hit;
349 trace_printk("%ld ns per entry\n", avg);
354 missed /= (long)time;
356 trace_printk("Total iterations per millisec: %ld\n",
359 /* it is possible that hit + missed will overflow and be zero */
360 if (!(hit + missed)) {
361 trace_printk("hit + missed overflowed and totalled zero!\n");
362 hit--; /* make it non zero */
365 /* Caculate the average time in nanosecs */
366 avg = NSEC_PER_MSEC / (hit + missed);
367 trace_printk("%ld ns per entry\n", avg);
371 static void wait_to_die(void)
373 set_current_state(TASK_INTERRUPTIBLE);
374 while (!kthread_should_stop()) {
376 set_current_state(TASK_INTERRUPTIBLE);
378 __set_current_state(TASK_RUNNING);
381 static int ring_buffer_consumer_thread(void *arg)
383 while (!break_test()) {
384 complete(&read_start);
386 ring_buffer_consumer();
388 set_current_state(TASK_INTERRUPTIBLE);
393 __set_current_state(TASK_RUNNING);
395 if (!kthread_should_stop())
401 static int ring_buffer_producer_thread(void *arg)
403 while (!break_test()) {
404 ring_buffer_reset(buffer);
407 wake_up_process(consumer);
408 wait_for_completion(&read_start);
411 ring_buffer_producer();
415 trace_printk("Sleeping for 10 secs\n");
416 set_current_state(TASK_INTERRUPTIBLE);
419 schedule_timeout(HZ * SLEEP_TIME);
423 __set_current_state(TASK_RUNNING);
424 if (!kthread_should_stop())
430 static int __init ring_buffer_benchmark_init(void)
434 /* make a one meg buffer in overwite mode */
435 buffer = ring_buffer_alloc(1000000, RB_FL_OVERWRITE);
439 if (!disable_reader) {
440 consumer = kthread_create(ring_buffer_consumer_thread,
441 NULL, "rb_consumer");
442 ret = PTR_ERR(consumer);
443 if (IS_ERR(consumer))
447 producer = kthread_run(ring_buffer_producer_thread,
448 NULL, "rb_producer");
449 ret = PTR_ERR(producer);
451 if (IS_ERR(producer))
455 * Run them as low-prio background tasks by default:
457 if (!disable_reader) {
458 if (consumer_fifo >= 0) {
459 struct sched_param param = {
460 .sched_priority = consumer_fifo
462 sched_setscheduler(consumer, SCHED_FIFO, ¶m);
464 set_user_nice(consumer, consumer_nice);
467 if (producer_fifo >= 0) {
468 struct sched_param param = {
469 .sched_priority = producer_fifo
471 sched_setscheduler(producer, SCHED_FIFO, ¶m);
473 set_user_nice(producer, producer_nice);
479 kthread_stop(consumer);
482 ring_buffer_free(buffer);
486 static void __exit ring_buffer_benchmark_exit(void)
488 kthread_stop(producer);
490 kthread_stop(consumer);
491 ring_buffer_free(buffer);
494 module_init(ring_buffer_benchmark_init);
495 module_exit(ring_buffer_benchmark_exit);
497 MODULE_AUTHOR("Steven Rostedt");
498 MODULE_DESCRIPTION("ring_buffer_benchmark");
499 MODULE_LICENSE("GPL");