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 read_events;
55 static enum event_status read_event(int cpu)
57 struct ring_buffer_event *event;
61 event = ring_buffer_consume(buffer, cpu, &ts);
65 entry = ring_buffer_event_data(event);
75 static enum event_status read_page(int cpu)
77 struct ring_buffer_event *event;
78 struct rb_page *rpage;
86 bpage = ring_buffer_alloc_read_page(buffer);
90 ret = ring_buffer_read_page(buffer, &bpage, PAGE_SIZE, cpu, 1);
93 commit = local_read(&rpage->commit);
94 for (i = 0; i < commit && !kill_test; i += inc) {
96 if (i >= (PAGE_SIZE - offsetof(struct rb_page, data))) {
102 event = (void *)&rpage->data[i];
103 switch (event->type_len) {
104 case RINGBUF_TYPE_PADDING:
105 /* We don't expect any padding */
108 case RINGBUF_TYPE_TIME_EXTEND:
112 entry = ring_buffer_event_data(event);
118 if (!event->array[0]) {
122 inc = event->array[0];
125 entry = ring_buffer_event_data(event);
131 inc = ((event->type_len + 1) * 4);
142 ring_buffer_free_read_page(buffer, bpage);
145 return EVENT_DROPPED;
149 static void ring_buffer_consumer(void)
151 /* toggle between reading pages and events */
155 while (!reader_finish && !kill_test) {
162 for_each_online_cpu(cpu) {
163 enum event_status stat;
166 stat = read_event(cpu);
168 stat = read_page(cpu);
172 if (stat == EVENT_FOUND)
175 } while (found && !kill_test);
177 set_current_state(TASK_INTERRUPTIBLE);
182 __set_current_state(TASK_RUNNING);
185 complete(&read_done);
188 static void ring_buffer_producer(void)
190 struct timeval start_tv;
191 struct timeval end_tv;
192 unsigned long long time;
193 unsigned long long entries;
194 unsigned long long overruns;
195 unsigned long missed = 0;
196 unsigned long hit = 0;
201 * Hammer the buffer for 10 secs (this may
202 * make the system stall)
204 pr_info("Starting ring buffer hammer\n");
205 do_gettimeofday(&start_tv);
207 struct ring_buffer_event *event;
210 event = ring_buffer_lock_reserve(buffer, 10);
215 entry = ring_buffer_event_data(event);
216 *entry = smp_processor_id();
217 ring_buffer_unlock_commit(buffer, event);
219 do_gettimeofday(&end_tv);
221 if (consumer && !(++cnt % wakeup_interval))
222 wake_up_process(consumer);
225 * If we are a non preempt kernel, the 10 second run will
226 * stop everything while it runs. Instead, we will call
227 * cond_resched and also add any time that was lost by a
232 } while (end_tv.tv_sec < (start_tv.tv_sec + RUN_TIME) && !kill_test);
233 pr_info("End ring buffer hammer\n");
236 /* Init both completions here to avoid races */
237 init_completion(&read_start);
238 init_completion(&read_done);
239 /* the completions must be visible before the finish var */
242 /* finish var visible before waking up the consumer */
244 wake_up_process(consumer);
245 wait_for_completion(&read_done);
248 time = end_tv.tv_sec - start_tv.tv_sec;
250 time += (long long)((long)end_tv.tv_usec - (long)start_tv.tv_usec);
252 entries = ring_buffer_entries(buffer);
253 overruns = ring_buffer_overruns(buffer);
257 pr_info("Time: %lld (usecs)\n", time);
258 pr_info("Overruns: %lld\n", overruns);
260 pr_info("Read: (reader disabled)\n");
262 pr_info("Read: %ld (by %s)\n", read,
263 read_events ? "events" : "pages");
264 pr_info("Entries: %lld\n", entries);
265 pr_info("Total: %lld\n", entries + overruns + read);
266 pr_info("Missed: %ld\n", missed);
267 pr_info("Hit: %ld\n", hit);
273 pr_info("TIME IS ZERO??\n");
275 pr_info("Entries per millisec: %ld\n", hit);
279 pr_info("%ld ns per entry\n", avg);
283 static void wait_to_die(void)
285 set_current_state(TASK_INTERRUPTIBLE);
286 while (!kthread_should_stop()) {
288 set_current_state(TASK_INTERRUPTIBLE);
290 __set_current_state(TASK_RUNNING);
293 static int ring_buffer_consumer_thread(void *arg)
295 while (!kthread_should_stop() && !kill_test) {
296 complete(&read_start);
298 ring_buffer_consumer();
300 set_current_state(TASK_INTERRUPTIBLE);
301 if (kthread_should_stop() || kill_test)
305 __set_current_state(TASK_RUNNING);
307 __set_current_state(TASK_RUNNING);
315 static int ring_buffer_producer_thread(void *arg)
317 init_completion(&read_start);
319 while (!kthread_should_stop() && !kill_test) {
320 ring_buffer_reset(buffer);
324 wake_up_process(consumer);
325 wait_for_completion(&read_start);
328 ring_buffer_producer();
330 pr_info("Sleeping for 10 secs\n");
331 set_current_state(TASK_INTERRUPTIBLE);
332 schedule_timeout(HZ * SLEEP_TIME);
333 __set_current_state(TASK_RUNNING);
342 static int __init ring_buffer_benchmark_init(void)
346 /* make a one meg buffer in overwite mode */
347 buffer = ring_buffer_alloc(1000000, RB_FL_OVERWRITE);
351 if (!disable_reader) {
352 consumer = kthread_create(ring_buffer_consumer_thread,
353 NULL, "rb_consumer");
354 ret = PTR_ERR(consumer);
355 if (IS_ERR(consumer))
359 producer = kthread_run(ring_buffer_producer_thread,
360 NULL, "rb_producer");
361 ret = PTR_ERR(producer);
363 if (IS_ERR(producer))
370 kthread_stop(consumer);
373 ring_buffer_free(buffer);
377 static void __exit ring_buffer_benchmark_exit(void)
379 kthread_stop(producer);
381 kthread_stop(consumer);
382 ring_buffer_free(buffer);
385 module_init(ring_buffer_benchmark_init);
386 module_exit(ring_buffer_benchmark_exit);
388 MODULE_AUTHOR("Steven Rostedt");
389 MODULE_DESCRIPTION("ring_buffer_benchmark");
390 MODULE_LICENSE("GPL");