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>
18 /* run time and sleep time in seconds */
22 /* number of events for writer to wake up the reader */
23 static int wakeup_interval = 100;
25 static int reader_finish;
26 static struct completion read_start;
27 static struct completion read_done;
29 static struct ring_buffer *buffer;
30 static struct task_struct *producer;
31 static struct task_struct *consumer;
32 static unsigned long read;
34 static int disable_reader;
35 module_param(disable_reader, uint, 0644);
36 MODULE_PARM_DESC(disable_reader, "only run producer");
38 static int write_iteration = 50;
39 module_param(write_iteration, uint, 0644);
40 MODULE_PARM_DESC(write_iteration, "# of writes between timestamp readings");
42 static int producer_nice = 19;
43 static int consumer_nice = 19;
45 static int producer_fifo = -1;
46 static int consumer_fifo = -1;
48 module_param(producer_nice, uint, 0644);
49 MODULE_PARM_DESC(producer_nice, "nice prio for producer");
51 module_param(consumer_nice, uint, 0644);
52 MODULE_PARM_DESC(consumer_nice, "nice prio for consumer");
54 module_param(producer_fifo, uint, 0644);
55 MODULE_PARM_DESC(producer_fifo, "fifo prio for producer");
57 module_param(consumer_fifo, uint, 0644);
58 MODULE_PARM_DESC(consumer_fifo, "fifo prio for consumer");
60 static int read_events;
77 static enum event_status read_event(int cpu)
79 struct ring_buffer_event *event;
83 event = ring_buffer_consume(buffer, cpu, &ts);
87 entry = ring_buffer_event_data(event);
97 static enum event_status read_page(int cpu)
99 struct ring_buffer_event *event;
100 struct rb_page *rpage;
101 unsigned long commit;
108 bpage = ring_buffer_alloc_read_page(buffer);
110 return EVENT_DROPPED;
112 ret = ring_buffer_read_page(buffer, &bpage, PAGE_SIZE, cpu, 1);
115 commit = local_read(&rpage->commit);
116 for (i = 0; i < commit && !kill_test; i += inc) {
118 if (i >= (PAGE_SIZE - offsetof(struct rb_page, data))) {
124 event = (void *)&rpage->data[i];
125 switch (event->type_len) {
126 case RINGBUF_TYPE_PADDING:
127 /* failed writes may be discarded events */
128 if (!event->time_delta)
130 inc = event->array[0] + 4;
132 case RINGBUF_TYPE_TIME_EXTEND:
136 entry = ring_buffer_event_data(event);
142 if (!event->array[0]) {
146 inc = event->array[0] + 4;
149 entry = ring_buffer_event_data(event);
155 inc = ((event->type_len + 1) * 4);
166 ring_buffer_free_read_page(buffer, bpage);
169 return EVENT_DROPPED;
173 static void ring_buffer_consumer(void)
175 /* toggle between reading pages and events */
179 while (!reader_finish && !kill_test) {
186 for_each_online_cpu(cpu) {
187 enum event_status stat;
190 stat = read_event(cpu);
192 stat = read_page(cpu);
196 if (stat == EVENT_FOUND)
199 } while (found && !kill_test);
201 set_current_state(TASK_INTERRUPTIBLE);
206 __set_current_state(TASK_RUNNING);
209 complete(&read_done);
212 static void ring_buffer_producer(void)
214 struct timeval start_tv;
215 struct timeval end_tv;
216 unsigned long long time;
217 unsigned long long entries;
218 unsigned long long overruns;
219 unsigned long missed = 0;
220 unsigned long hit = 0;
225 * Hammer the buffer for 10 secs (this may
226 * make the system stall)
228 trace_printk("Starting ring buffer hammer\n");
229 do_gettimeofday(&start_tv);
231 struct ring_buffer_event *event;
235 for (i = 0; i < write_iteration; i++) {
236 event = ring_buffer_lock_reserve(buffer, 10);
241 entry = ring_buffer_event_data(event);
242 *entry = smp_processor_id();
243 ring_buffer_unlock_commit(buffer, event);
246 do_gettimeofday(&end_tv);
249 if (consumer && !(cnt % wakeup_interval))
250 wake_up_process(consumer);
252 #ifndef CONFIG_PREEMPT
254 * If we are a non preempt kernel, the 10 second run will
255 * stop everything while it runs. Instead, we will call
256 * cond_resched and also add any time that was lost by a
259 * Do a cond resched at the same frequency we would wake up
262 if (cnt % wakeup_interval)
266 } while (end_tv.tv_sec < (start_tv.tv_sec + RUN_TIME) && !kill_test);
267 trace_printk("End ring buffer hammer\n");
270 /* Init both completions here to avoid races */
271 init_completion(&read_start);
272 init_completion(&read_done);
273 /* the completions must be visible before the finish var */
276 /* finish var visible before waking up the consumer */
278 wake_up_process(consumer);
279 wait_for_completion(&read_done);
282 time = end_tv.tv_sec - start_tv.tv_sec;
283 time *= USEC_PER_SEC;
284 time += (long long)((long)end_tv.tv_usec - (long)start_tv.tv_usec);
286 entries = ring_buffer_entries(buffer);
287 overruns = ring_buffer_overruns(buffer);
290 trace_printk("ERROR!\n");
292 if (!disable_reader) {
293 if (consumer_fifo < 0)
294 trace_printk("Running Consumer at nice: %d\n",
297 trace_printk("Running Consumer at SCHED_FIFO %d\n",
300 if (producer_fifo < 0)
301 trace_printk("Running Producer at nice: %d\n",
304 trace_printk("Running Producer at SCHED_FIFO %d\n",
307 /* Let the user know that the test is running at low priority */
308 if (producer_fifo < 0 && consumer_fifo < 0 &&
309 producer_nice == 19 && consumer_nice == 19)
310 trace_printk("WARNING!!! This test is running at lowest priority.\n");
312 trace_printk("Time: %lld (usecs)\n", time);
313 trace_printk("Overruns: %lld\n", overruns);
315 trace_printk("Read: (reader disabled)\n");
317 trace_printk("Read: %ld (by %s)\n", read,
318 read_events ? "events" : "pages");
319 trace_printk("Entries: %lld\n", entries);
320 trace_printk("Total: %lld\n", entries + overruns + read);
321 trace_printk("Missed: %ld\n", missed);
322 trace_printk("Hit: %ld\n", hit);
324 /* Convert time from usecs to millisecs */
325 do_div(time, USEC_PER_MSEC);
329 trace_printk("TIME IS ZERO??\n");
331 trace_printk("Entries per millisec: %ld\n", hit);
334 /* Calculate the average time in nanosecs */
335 avg = NSEC_PER_MSEC / hit;
336 trace_printk("%ld ns per entry\n", avg);
341 missed /= (long)time;
343 trace_printk("Total iterations per millisec: %ld\n",
346 /* it is possible that hit + missed will overflow and be zero */
347 if (!(hit + missed)) {
348 trace_printk("hit + missed overflowed and totalled zero!\n");
349 hit--; /* make it non zero */
352 /* Caculate the average time in nanosecs */
353 avg = NSEC_PER_MSEC / (hit + missed);
354 trace_printk("%ld ns per entry\n", avg);
358 static void wait_to_die(void)
360 set_current_state(TASK_INTERRUPTIBLE);
361 while (!kthread_should_stop()) {
363 set_current_state(TASK_INTERRUPTIBLE);
365 __set_current_state(TASK_RUNNING);
368 static int ring_buffer_consumer_thread(void *arg)
370 while (!kthread_should_stop() && !kill_test) {
371 complete(&read_start);
373 ring_buffer_consumer();
375 set_current_state(TASK_INTERRUPTIBLE);
376 if (kthread_should_stop() || kill_test)
380 __set_current_state(TASK_RUNNING);
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);
408 __set_current_state(TASK_RUNNING);
417 static int __init ring_buffer_benchmark_init(void)
421 /* make a one meg buffer in overwite mode */
422 buffer = ring_buffer_alloc(1000000, RB_FL_OVERWRITE);
426 if (!disable_reader) {
427 consumer = kthread_create(ring_buffer_consumer_thread,
428 NULL, "rb_consumer");
429 ret = PTR_ERR(consumer);
430 if (IS_ERR(consumer))
434 producer = kthread_run(ring_buffer_producer_thread,
435 NULL, "rb_producer");
436 ret = PTR_ERR(producer);
438 if (IS_ERR(producer))
442 * Run them as low-prio background tasks by default:
444 if (!disable_reader) {
445 if (consumer_fifo >= 0) {
446 struct sched_param param = {
447 .sched_priority = consumer_fifo
449 sched_setscheduler(consumer, SCHED_FIFO, ¶m);
451 set_user_nice(consumer, consumer_nice);
454 if (producer_fifo >= 0) {
455 struct sched_param param = {
456 .sched_priority = consumer_fifo
458 sched_setscheduler(producer, SCHED_FIFO, ¶m);
460 set_user_nice(producer, producer_nice);
466 kthread_stop(consumer);
469 ring_buffer_free(buffer);
473 static void __exit ring_buffer_benchmark_exit(void)
475 kthread_stop(producer);
477 kthread_stop(consumer);
478 ring_buffer_free(buffer);
481 module_init(ring_buffer_benchmark_init);
482 module_exit(ring_buffer_benchmark_exit);
484 MODULE_AUTHOR("Steven Rostedt");
485 MODULE_DESCRIPTION("ring_buffer_benchmark");
486 MODULE_LICENSE("GPL");