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// 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 ring_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 = -1;
static int consumer_fifo = -1;
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, "fifo prio for producer");
module_param(consumer_fifo, int, 0644);
MODULE_PARM_DESC(consumer_fifo, "fifo prio for consumer");
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 second run will
* stop everything while it runs. Instead, we will call
* cond_resched and also add any time that was lost by a
* rescedule.
*
* 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(&a
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