diff options
Diffstat (limited to 'kernel/trace/ring_buffer_benchmark.c')
| -rw-r--r-- | kernel/trace/ring_buffer_benchmark.c | 497 |
1 files changed, 497 insertions, 0 deletions
diff --git a/kernel/trace/ring_buffer_benchmark.c b/kernel/trace/ring_buffer_benchmark.c new file mode 100644 index 000000000..78e576575 --- /dev/null +++ b/kernel/trace/ring_buffer_benchmark.c @@ -0,0 +1,497 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * ring buffer tester and benchmark + * + * Copyright (C) 2009 Steven Rostedt <srostedt@redhat.com> + */ +#include <linux/ring_buffer.h> +#include <linux/completion.h> +#include <linux/kthread.h> +#include <uapi/linux/sched/types.h> +#include <linux/module.h> +#include <linux/ktime.h> +#include <asm/local.h> + +struct rb_page { + u64 ts; + local_t commit; + char data[4080]; +}; + +/* run time and sleep time in seconds */ +#define RUN_TIME 10ULL +#define SLEEP_TIME 10 + +/* number of events for writer to wake up the reader */ +static int wakeup_interval = 100; + +static int reader_finish; +static DECLARE_COMPLETION(read_start); +static DECLARE_COMPLETION(read_done); + +static struct trace_buffer *buffer; +static struct task_struct *producer; +static struct task_struct *consumer; +static unsigned long read; + +static unsigned int disable_reader; +module_param(disable_reader, uint, 0644); +MODULE_PARM_DESC(disable_reader, "only run producer"); + +static unsigned int write_iteration = 50; +module_param(write_iteration, uint, 0644); +MODULE_PARM_DESC(write_iteration, "# of writes between timestamp readings"); + +static int producer_nice = MAX_NICE; +static int consumer_nice = MAX_NICE; + +static int producer_fifo; +static int consumer_fifo; + +module_param(producer_nice, int, 0644); +MODULE_PARM_DESC(producer_nice, "nice prio for producer"); + +module_param(consumer_nice, int, 0644); +MODULE_PARM_DESC(consumer_nice, "nice prio for consumer"); + +module_param(producer_fifo, int, 0644); +MODULE_PARM_DESC(producer_fifo, "use fifo for producer: 0 - disabled, 1 - low prio, 2 - fifo"); + +module_param(consumer_fifo, int, 0644); +MODULE_PARM_DESC(consumer_fifo, "use fifo for consumer: 0 - disabled, 1 - low prio, 2 - fifo"); + +static int read_events; + +static int test_error; + +#define TEST_ERROR() \ + do { \ + if (!test_error) { \ + test_error = 1; \ + WARN_ON(1); \ + } \ + } while (0) + +enum event_status { + EVENT_FOUND, + EVENT_DROPPED, +}; + +static bool break_test(void) +{ + return test_error || kthread_should_stop(); +} + +static enum event_status read_event(int cpu) +{ + struct ring_buffer_event *event; + int *entry; + u64 ts; + + event = ring_buffer_consume(buffer, cpu, &ts, NULL); + if (!event) + return EVENT_DROPPED; + + entry = ring_buffer_event_data(event); + if (*entry != cpu) { + TEST_ERROR(); + return EVENT_DROPPED; + } + + read++; + return EVENT_FOUND; +} + +static enum event_status read_page(int cpu) +{ + struct ring_buffer_event *event; + struct rb_page *rpage; + unsigned long commit; + void *bpage; + int *entry; + int ret; + int inc; + int i; + + bpage = ring_buffer_alloc_read_page(buffer, cpu); + if (IS_ERR(bpage)) + return EVENT_DROPPED; + + ret = ring_buffer_read_page(buffer, &bpage, PAGE_SIZE, cpu, 1); + if (ret >= 0) { + rpage = bpage; + /* The commit may have missed event flags set, clear them */ + commit = local_read(&rpage->commit) & 0xfffff; + for (i = 0; i < commit && !test_error ; i += inc) { + + if (i >= (PAGE_SIZE - offsetof(struct rb_page, data))) { + TEST_ERROR(); + break; + } + + inc = -1; + event = (void *)&rpage->data[i]; + switch (event->type_len) { + case RINGBUF_TYPE_PADDING: + /* failed writes may be discarded events */ + if (!event->time_delta) + TEST_ERROR(); + inc = event->array[0] + 4; + break; + case RINGBUF_TYPE_TIME_EXTEND: + inc = 8; + break; + case 0: + entry = ring_buffer_event_data(event); + if (*entry != cpu) { + TEST_ERROR(); + break; + } + read++; + if (!event->array[0]) { + TEST_ERROR(); + break; + } + inc = event->array[0] + 4; + break; + default: + entry = ring_buffer_event_data(event); + if (*entry != cpu) { + TEST_ERROR(); + break; + } + read++; + inc = ((event->type_len + 1) * 4); + } + if (test_error) + break; + + if (inc <= 0) { + TEST_ERROR(); + break; + } + } + } + ring_buffer_free_read_page(buffer, cpu, bpage); + + if (ret < 0) + return EVENT_DROPPED; + return EVENT_FOUND; +} + +static void ring_buffer_consumer(void) +{ + /* toggle between reading pages and events */ + read_events ^= 1; + + read = 0; + /* + * Continue running until the producer specifically asks to stop + * and is ready for the completion. + */ + while (!READ_ONCE(reader_finish)) { + int found = 1; + + while (found && !test_error) { + int cpu; + + found = 0; + for_each_online_cpu(cpu) { + enum event_status stat; + + if (read_events) + stat = read_event(cpu); + else + stat = read_page(cpu); + + if (test_error) + break; + + if (stat == EVENT_FOUND) + found = 1; + + } + } + + /* Wait till the producer wakes us up when there is more data + * available or when the producer wants us to finish reading. + */ + set_current_state(TASK_INTERRUPTIBLE); + if (reader_finish) + break; + + schedule(); + } + __set_current_state(TASK_RUNNING); + reader_finish = 0; + complete(&read_done); +} + +static void ring_buffer_producer(void) +{ + ktime_t start_time, end_time, timeout; + unsigned long long time; + unsigned long long entries; + unsigned long long overruns; + unsigned long missed = 0; + unsigned long hit = 0; + unsigned long avg; + int cnt = 0; + + /* + * Hammer the buffer for 10 secs (this may + * make the system stall) + */ + trace_printk("Starting ring buffer hammer\n"); + start_time = ktime_get(); + timeout = ktime_add_ns(start_time, RUN_TIME * NSEC_PER_SEC); + do { + struct ring_buffer_event *event; + int *entry; + int i; + + for (i = 0; i < write_iteration; i++) { + event = ring_buffer_lock_reserve(buffer, 10); + if (!event) { + missed++; + } else { + hit++; + entry = ring_buffer_event_data(event); + *entry = smp_processor_id(); + ring_buffer_unlock_commit(buffer, event); + } + } + end_time = ktime_get(); + + cnt++; + if (consumer && !(cnt % wakeup_interval)) + wake_up_process(consumer); + +#ifndef CONFIG_PREEMPTION + /* + * If we are a non preempt kernel, the 10 seconds run will + * stop everything while it runs. Instead, we will call + * cond_resched and also add any time that was lost by a + * reschedule. + * + * Do a cond resched at the same frequency we would wake up + * the reader. + */ + if (cnt % wakeup_interval) + cond_resched(); +#endif + } while (ktime_before(end_time, timeout) && !break_test()); + trace_printk("End ring buffer hammer\n"); + + if (consumer) { + /* Init both completions here to avoid races */ + init_completion(&read_start); + init_completion(&read_done); + /* the completions must be visible before the finish var */ + smp_wmb(); + reader_finish = 1; + wake_up_process(consumer); + wait_for_completion(&read_done); + } + + time = ktime_us_delta(end_time, start_time); + + entries = ring_buffer_entries(buffer); + overruns = ring_buffer_overruns(buffer); + + if (test_error) + trace_printk("ERROR!\n"); + + if (!disable_reader) { + if (consumer_fifo) + trace_printk("Running Consumer at SCHED_FIFO %s\n", + consumer_fifo == 1 ? "low" : "high"); + else + trace_printk("Running Consumer at nice: %d\n", + consumer_nice); + } + if (producer_fifo) + trace_printk("Running Producer at SCHED_FIFO %s\n", + producer_fifo == 1 ? "low" : "high"); + else + trace_printk("Running Producer at nice: %d\n", + producer_nice); + + /* Let the user know that the test is running at low priority */ + if (!producer_fifo && !consumer_fifo && + producer_nice == MAX_NICE && consumer_nice == MAX_NICE) + trace_printk("WARNING!!! This test is running at lowest priority.\n"); + + trace_printk("Time: %lld (usecs)\n", time); + trace_printk("Overruns: %lld\n", overruns); + if (disable_reader) + trace_printk("Read: (reader disabled)\n"); + else + trace_printk("Read: %ld (by %s)\n", read, + read_events ? "events" : "pages"); + trace_printk("Entries: %lld\n", entries); + trace_printk("Total: %lld\n", entries + overruns + read); + trace_printk("Missed: %ld\n", missed); + trace_printk("Hit: %ld\n", hit); + + /* Convert time from usecs to millisecs */ + do_div(time, USEC_PER_MSEC); + if (time) + hit /= (long)time; + else + trace_printk("TIME IS ZERO??\n"); + + trace_printk("Entries per millisec: %ld\n", hit); + + if (hit) { + /* Calculate the average time in nanosecs */ + avg = NSEC_PER_MSEC / hit; + trace_printk("%ld ns per entry\n", avg); + } + + if (missed) { + if (time) + missed /= (long)time; + + trace_printk("Total iterations per millisec: %ld\n", + hit + missed); + + /* it is possible that hit + missed will overflow and be zero */ + if (!(hit + missed)) { + trace_printk("hit + missed overflowed and totalled zero!\n"); + hit--; /* make it non zero */ + } + + /* Calculate the average time in nanosecs */ + avg = NSEC_PER_MSEC / (hit + missed); + trace_printk("%ld ns per entry\n", avg); + } +} + +static void wait_to_die(void) +{ + set_current_state(TASK_INTERRUPTIBLE); + while (!kthread_should_stop()) { + schedule(); + set_current_state(TASK_INTERRUPTIBLE); + } + __set_current_state(TASK_RUNNING); +} + +static int ring_buffer_consumer_thread(void *arg) +{ + while (!break_test()) { + complete(&read_start); + + ring_buffer_consumer(); + + set_current_state(TASK_INTERRUPTIBLE); + if (break_test()) + break; + schedule(); + } + __set_current_state(TASK_RUNNING); + + if (!kthread_should_stop()) + wait_to_die(); + + return 0; +} + +static int ring_buffer_producer_thread(void *arg) +{ + while (!break_test()) { + ring_buffer_reset(buffer); + + if (consumer) { + wake_up_process(consumer); + wait_for_completion(&read_start); + } + + ring_buffer_producer(); + if (break_test()) + goto out_kill; + + trace_printk("Sleeping for 10 secs\n"); + set_current_state(TASK_INTERRUPTIBLE); + if (break_test()) + goto out_kill; + schedule_timeout(HZ * SLEEP_TIME); + } + +out_kill: + __set_current_state(TASK_RUNNING); + if (!kthread_should_stop()) + wait_to_die(); + + return 0; +} + +static int __init ring_buffer_benchmark_init(void) +{ + int ret; + + /* make a one meg buffer in overwite mode */ + buffer = ring_buffer_alloc(1000000, RB_FL_OVERWRITE); + if (!buffer) + return -ENOMEM; + + if (!disable_reader) { + consumer = kthread_create(ring_buffer_consumer_thread, + NULL, "rb_consumer"); + ret = PTR_ERR(consumer); + if (IS_ERR(consumer)) + goto out_fail; + } + + producer = kthread_run(ring_buffer_producer_thread, + NULL, "rb_producer"); + ret = PTR_ERR(producer); + + if (IS_ERR(producer)) + goto out_kill; + + /* + * Run them as low-prio background tasks by default: + */ + if (!disable_reader) { + if (consumer_fifo >= 2) + sched_set_fifo(consumer); + else if (consumer_fifo == 1) + sched_set_fifo_low(consumer); + else + set_user_nice(consumer, consumer_nice); + } + + if (producer_fifo >= 2) + sched_set_fifo(producer); + else if (producer_fifo == 1) + sched_set_fifo_low(producer); + else + set_user_nice(producer, producer_nice); + + return 0; + + out_kill: + if (consumer) + kthread_stop(consumer); + + out_fail: + ring_buffer_free(buffer); + return ret; +} + +static void __exit ring_buffer_benchmark_exit(void) +{ + kthread_stop(producer); + if (consumer) + kthread_stop(consumer); + ring_buffer_free(buffer); +} + +module_init(ring_buffer_benchmark_init); +module_exit(ring_buffer_benchmark_exit); + +MODULE_AUTHOR("Steven Rostedt"); +MODULE_DESCRIPTION("ring_buffer_benchmark"); +MODULE_LICENSE("GPL"); |