Root/kernel/trace/ring_buffer_benchmark.c

1/*
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>
11#include <asm/local.h>
12
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
39static int write_iteration = 50;
40module_param(write_iteration, uint, 0644);
41MODULE_PARM_DESC(write_iteration, "# of writes between timestamp readings");
42
43static 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
61static 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
84    event = ring_buffer_consume(buffer, cpu, &ts, NULL);
85    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
109    bpage = ring_buffer_alloc_read_page(buffer);
110    if (!bpage)
111        return EVENT_DROPPED;
112
113    ret = ring_buffer_read_page(buffer, &bpage, PAGE_SIZE, cpu, 1);
114    if (ret >= 0) {
115        rpage = bpage;
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) {
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:
129                /* failed writes may be discarded events */
130                if (!event->time_delta)
131                    KILL_TEST();
132                inc = event->array[0] + 4;
133                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                }
148                inc = event->array[0] + 4;
149                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     */
230    trace_printk("Starting ring buffer hammer\n");
231    do_gettimeofday(&start_tv);
232    do {
233        struct ring_buffer_event *event;
234        int *entry;
235        int i;
236
237        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            }
247        }
248        do_gettimeofday(&end_tv);
249
250        cnt++;
251        if (consumer && !(cnt % wakeup_interval))
252            wake_up_process(consumer);
253
254#ifndef CONFIG_PREEMPT
255        /*
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.
260         *
261         * Do a cond resched at the same frequency we would wake up
262         * the reader.
263         */
264        if (cnt % wakeup_interval)
265            cond_resched();
266#endif
267
268    } while (end_tv.tv_sec < (start_tv.tv_sec + RUN_TIME) && !kill_test);
269    trace_printk("End ring buffer hammer\n");
270
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;
285    time *= USEC_PER_SEC;
286    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)
292        trace_printk("ERROR!\n");
293
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
314    trace_printk("Time: %lld (usecs)\n", time);
315    trace_printk("Overruns: %lld\n", overruns);
316    if (disable_reader)
317        trace_printk("Read: (reader disabled)\n");
318    else
319        trace_printk("Read: %ld (by %s)\n", read,
320            read_events ? "events" : "pages");
321    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);
325
326    /* Convert time from usecs to millisecs */
327    do_div(time, USEC_PER_MSEC);
328    if (time)
329        hit /= (long)time;
330    else
331        trace_printk("TIME IS ZERO??\n");
332
333    trace_printk("Entries per millisec: %ld\n", hit);
334
335    if (hit) {
336        /* Calculate the average time in nanosecs */
337        avg = NSEC_PER_MSEC / hit;
338        trace_printk("%ld ns per entry\n", avg);
339    }
340
341    if (missed) {
342        if (time)
343            missed /= (long)time;
344
345        trace_printk("Total iterations per millisec: %ld\n",
346                 hit + missed);
347
348        /* it is possible that hit + missed will overflow and be zero */
349        if (!(hit + missed)) {
350            trace_printk("hit + missed overflowed and totalled zero!\n");
351            hit--; /* make it non zero */
352        }
353
354        /* Caculate the average time in nanosecs */
355        avg = NSEC_PER_MSEC / (hit + missed);
356        trace_printk("%ld ns per entry\n", avg);
357    }
358}
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
407        trace_printk("Sleeping for 10 secs\n");
408        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
443    /*
444     * Run them as low-prio background tasks by default:
445     */
446    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);
463
464    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");
489

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