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/time.h>
11 #include <asm/local.h>
19 /* run time and sleep time in seconds */
23 /* number of events for writer to wake up the reader */
24 static int wakeup_interval = 100;
26 static int reader_finish;
27 static struct completion read_start;
28 static struct 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 int disable_reader;
36 module_param(disable_reader, uint, 0644);
37 MODULE_PARM_DESC(disable_reader, "only run producer");
39 static 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, uint, 0644);
50 MODULE_PARM_DESC(producer_nice, "nice prio for producer");
52 module_param(consumer_nice, uint, 0644);
53 MODULE_PARM_DESC(consumer_nice, "nice prio for consumer");
55 module_param(producer_fifo, uint, 0644);
56 MODULE_PARM_DESC(producer_fifo, "fifo prio for producer");
58 module_param(consumer_fifo, uint, 0644);
59 MODULE_PARM_DESC(consumer_fifo, "fifo prio for consumer");
61 static int read_events;
78 static enum event_status read_event(int cpu)
80 struct ring_buffer_event *event;
84 event = ring_buffer_consume(buffer, cpu, &ts, NULL);
88 entry = ring_buffer_event_data(event);
98 static enum event_status read_page(int cpu)
100 struct ring_buffer_event *event;
101 struct rb_page *rpage;
102 unsigned long commit;
109 bpage = ring_buffer_alloc_read_page(buffer, cpu);
111 return EVENT_DROPPED;
113 ret = ring_buffer_read_page(buffer, &bpage, PAGE_SIZE, cpu, 1);
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) {
120 if (i >= (PAGE_SIZE - offsetof(struct rb_page, data))) {
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)
132 inc = event->array[0] + 4;
134 case RINGBUF_TYPE_TIME_EXTEND:
138 entry = ring_buffer_event_data(event);
144 if (!event->array[0]) {
148 inc = event->array[0] + 4;
151 entry = ring_buffer_event_data(event);
157 inc = ((event->type_len + 1) * 4);
168 ring_buffer_free_read_page(buffer, bpage);
171 return EVENT_DROPPED;
175 static void ring_buffer_consumer(void)
177 /* toggle between reading pages and events */
181 while (!reader_finish && !kill_test) {
188 for_each_online_cpu(cpu) {
189 enum event_status stat;
192 stat = read_event(cpu);
194 stat = read_page(cpu);
198 if (stat == EVENT_FOUND)
201 } while (found && !kill_test);
203 set_current_state(TASK_INTERRUPTIBLE);
210 complete(&read_done);
213 static void ring_buffer_producer(void)
215 struct timeval start_tv;
216 struct timeval end_tv;
217 unsigned long long time;
218 unsigned long long entries;
219 unsigned long long overruns;
220 unsigned long missed = 0;
221 unsigned long hit = 0;
226 * Hammer the buffer for 10 secs (this may
227 * make the system stall)
229 trace_printk("Starting ring buffer hammer\n");
230 do_gettimeofday(&start_tv);
232 struct ring_buffer_event *event;
236 for (i = 0; i < write_iteration; i++) {
237 event = ring_buffer_lock_reserve(buffer, 10);
242 entry = ring_buffer_event_data(event);
243 *entry = smp_processor_id();
244 ring_buffer_unlock_commit(buffer, event);
247 do_gettimeofday(&end_tv);
250 if (consumer && !(cnt % wakeup_interval))
251 wake_up_process(consumer);
253 #ifndef CONFIG_PREEMPT
255 * If we are a non preempt kernel, the 10 second run will
256 * stop everything while it runs. Instead, we will call
257 * cond_resched and also add any time that was lost by a
260 * Do a cond resched at the same frequency we would wake up
263 if (cnt % wakeup_interval)
267 } while (end_tv.tv_sec < (start_tv.tv_sec + RUN_TIME) && !kill_test);
268 trace_printk("End ring buffer hammer\n");
271 /* Init both completions here to avoid races */
272 init_completion(&read_start);
273 init_completion(&read_done);
274 /* the completions must be visible before the finish var */
277 /* finish var visible before waking up the consumer */
279 wake_up_process(consumer);
280 wait_for_completion(&read_done);
283 time = end_tv.tv_sec - start_tv.tv_sec;
284 time *= USEC_PER_SEC;
285 time += (long long)((long)end_tv.tv_usec - (long)start_tv.tv_usec);
287 entries = ring_buffer_entries(buffer);
288 overruns = ring_buffer_overruns(buffer);
291 trace_printk("ERROR!\n");
293 if (!disable_reader) {
294 if (consumer_fifo < 0)
295 trace_printk("Running Consumer at nice: %d\n",
298 trace_printk("Running Consumer at SCHED_FIFO %d\n",
301 if (producer_fifo < 0)
302 trace_printk("Running Producer at nice: %d\n",
305 trace_printk("Running Producer at SCHED_FIFO %d\n",
308 /* Let the user know that the test is running at low priority */
309 if (producer_fifo < 0 && consumer_fifo < 0 &&
310 producer_nice == MAX_NICE && consumer_nice == MAX_NICE)
311 trace_printk("WARNING!!! This test is running at lowest priority.\n");
313 trace_printk("Time: %lld (usecs)\n", time);
314 trace_printk("Overruns: %lld\n", overruns);
316 trace_printk("Read: (reader disabled)\n");
318 trace_printk("Read: %ld (by %s)\n", read,
319 read_events ? "events" : "pages");
320 trace_printk("Entries: %lld\n", entries);
321 trace_printk("Total: %lld\n", entries + overruns + read);
322 trace_printk("Missed: %ld\n", missed);
323 trace_printk("Hit: %ld\n", hit);
325 /* Convert time from usecs to millisecs */
326 do_div(time, USEC_PER_MSEC);
330 trace_printk("TIME IS ZERO??\n");
332 trace_printk("Entries per millisec: %ld\n", hit);
335 /* Calculate the average time in nanosecs */
336 avg = NSEC_PER_MSEC / hit;
337 trace_printk("%ld ns per entry\n", avg);
342 missed /= (long)time;
344 trace_printk("Total iterations per millisec: %ld\n",
347 /* it is possible that hit + missed will overflow and be zero */
348 if (!(hit + missed)) {
349 trace_printk("hit + missed overflowed and totalled zero!\n");
350 hit--; /* make it non zero */
353 /* Caculate the average time in nanosecs */
354 avg = NSEC_PER_MSEC / (hit + missed);
355 trace_printk("%ld ns per entry\n", avg);
359 static void wait_to_die(void)
361 set_current_state(TASK_INTERRUPTIBLE);
362 while (!kthread_should_stop()) {
364 set_current_state(TASK_INTERRUPTIBLE);
366 __set_current_state(TASK_RUNNING);
369 static int ring_buffer_consumer_thread(void *arg)
371 while (!kthread_should_stop() && !kill_test) {
372 complete(&read_start);
374 ring_buffer_consumer();
376 set_current_state(TASK_INTERRUPTIBLE);
377 if (kthread_should_stop() || kill_test)
382 __set_current_state(TASK_RUNNING);
390 static int ring_buffer_producer_thread(void *arg)
392 init_completion(&read_start);
394 while (!kthread_should_stop() && !kill_test) {
395 ring_buffer_reset(buffer);
399 wake_up_process(consumer);
400 wait_for_completion(&read_start);
403 ring_buffer_producer();
405 trace_printk("Sleeping for 10 secs\n");
406 set_current_state(TASK_INTERRUPTIBLE);
407 schedule_timeout(HZ * SLEEP_TIME);
416 static int __init ring_buffer_benchmark_init(void)
420 /* make a one meg buffer in overwite mode */
421 buffer = ring_buffer_alloc(1000000, RB_FL_OVERWRITE);
425 if (!disable_reader) {
426 consumer = kthread_create(ring_buffer_consumer_thread,
427 NULL, "rb_consumer");
428 ret = PTR_ERR(consumer);
429 if (IS_ERR(consumer))
433 producer = kthread_run(ring_buffer_producer_thread,
434 NULL, "rb_producer");
435 ret = PTR_ERR(producer);
437 if (IS_ERR(producer))
441 * Run them as low-prio background tasks by default:
443 if (!disable_reader) {
444 if (consumer_fifo >= 0) {
445 struct sched_param param = {
446 .sched_priority = consumer_fifo
448 sched_setscheduler(consumer, SCHED_FIFO, ¶m);
450 set_user_nice(consumer, consumer_nice);
453 if (producer_fifo >= 0) {
454 struct sched_param param = {
455 .sched_priority = consumer_fifo
457 sched_setscheduler(producer, SCHED_FIFO, ¶m);
459 set_user_nice(producer, producer_nice);
465 kthread_stop(consumer);
468 ring_buffer_free(buffer);
472 static void __exit ring_buffer_benchmark_exit(void)
474 kthread_stop(producer);
476 kthread_stop(consumer);
477 ring_buffer_free(buffer);
480 module_init(ring_buffer_benchmark_init);
481 module_exit(ring_buffer_benchmark_exit);
483 MODULE_AUTHOR("Steven Rostedt");
484 MODULE_DESCRIPTION("ring_buffer_benchmark");
485 MODULE_LICENSE("GPL");