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-rw-r--r--kernel/trace/Kconfig16
-rw-r--r--kernel/trace/Makefile1
-rw-r--r--kernel/trace/ring_buffer_benchmark.c379
3 files changed, 396 insertions, 0 deletions
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 450d3c2cfbd..50f62a296e1 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -471,6 +471,22 @@ config MMIOTRACE_TEST
Say N, unless you absolutely know what you are doing.
+config RING_BUFFER_BENCHMARK
+ tristate "Ring buffer benchmark stress tester"
+ depends on RING_BUFFER
+ help
+ This option creates a test to stress the ring buffer and bench mark it.
+ It creates its own ring buffer such that it will not interfer with
+ any other users of the ring buffer (such as ftrace). It then creates
+ a producer and consumer that will run for 10 seconds and sleep for
+ 10 seconds. Each interval it will print out the number of events
+ it recorded and give a rough estimate of how long each iteration took.
+
+ It does not disable interrupts or raise its priority, so it may be
+ affected by processes that are running.
+
+ If unsure, say N
+
endif # FTRACE
endif # TRACING_SUPPORT
diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
index fb9d7f96489..7c34cbfff96 100644
--- a/kernel/trace/Makefile
+++ b/kernel/trace/Makefile
@@ -17,6 +17,7 @@ endif
obj-$(CONFIG_FUNCTION_TRACER) += libftrace.o
obj-$(CONFIG_RING_BUFFER) += ring_buffer.o
+obj-$(CONFIG_RING_BUFFER_BENCHMARK) += ring_buffer_benchmark.o
obj-$(CONFIG_TRACING) += trace.o
obj-$(CONFIG_TRACING) += trace_clock.o
diff --git a/kernel/trace/ring_buffer_benchmark.c b/kernel/trace/ring_buffer_benchmark.c
new file mode 100644
index 00000000000..747244acb8f
--- /dev/null
+++ b/kernel/trace/ring_buffer_benchmark.c
@@ -0,0 +1,379 @@
+/*
+ * 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 <linux/module.h>
+#include <linux/time.h>
+
+struct rb_page {
+ u64 ts;
+ local_t commit;
+ char data[4080];
+};
+
+/* run time and sleep time in seconds */
+#define RUN_TIME 10
+#define SLEEP_TIME 10
+
+/* number of events for writer to wake up the reader */
+static int wakeup_interval = 100;
+
+static int reader_finish;
+static struct completion read_start;
+static struct completion read_done;
+
+static struct ring_buffer *buffer;
+static struct task_struct *producer;
+static struct task_struct *consumer;
+static unsigned long read;
+
+static int disable_reader;
+module_param(disable_reader, uint, 0644);
+MODULE_PARM_DESC(disable_reader, "only run producer");
+
+static int read_events;
+
+static int kill_test;
+
+#define KILL_TEST() \
+ do { \
+ if (!kill_test) { \
+ kill_test = 1; \
+ WARN_ON(1); \
+ } \
+ } while (0)
+
+enum event_status {
+ EVENT_FOUND,
+ EVENT_DROPPED,
+};
+
+static enum event_status read_event(int cpu)
+{
+ struct ring_buffer_event *event;
+ int *entry;
+ u64 ts;
+
+ event = ring_buffer_consume(buffer, cpu, &ts);
+ if (!event)
+ return EVENT_DROPPED;
+
+ entry = ring_buffer_event_data(event);
+ if (*entry != cpu) {
+ KILL_TEST();
+ 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);
+ ret = ring_buffer_read_page(buffer, &bpage, PAGE_SIZE, cpu, 1);
+ if (ret >= 0) {
+ rpage = bpage;
+ commit = local_read(&rpage->commit);
+ for (i = 0; i < commit && !kill_test; i += inc) {
+
+ if (i >= (PAGE_SIZE - offsetof(struct rb_page, data))) {
+ KILL_TEST();
+ break;
+ }
+
+ inc = -1;
+ event = (void *)&rpage->data[i];
+ switch (event->type_len) {
+ case RINGBUF_TYPE_PADDING:
+ /* We don't expect any padding */
+ KILL_TEST();
+ break;
+ case RINGBUF_TYPE_TIME_EXTEND:
+ inc = 8;
+ break;
+ case 0:
+ entry = ring_buffer_event_data(event);
+ if (*entry != cpu) {
+ KILL_TEST();
+ break;
+ }
+ read++;
+ if (!event->array[0]) {
+ KILL_TEST();
+ break;
+ }
+ inc = event->array[0];
+ break;
+ default:
+ entry = ring_buffer_event_data(event);
+ if (*entry != cpu) {
+ KILL_TEST();
+ break;
+ }
+ read++;
+ inc = ((event->type_len + 1) * 4);
+ }
+ if (kill_test)
+ break;
+
+ if (inc <= 0) {
+ KILL_TEST();
+ break;
+ }
+ }
+ }
+ ring_buffer_free_read_page(buffer, 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;
+ while (!reader_finish && !kill_test) {
+ int found;
+
+ do {
+ 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 (kill_test)
+ break;
+ if (stat == EVENT_FOUND)
+ found = 1;
+ }
+ } while (found && !kill_test);
+
+ 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)
+{
+ struct timeval start_tv;
+ struct timeval end_tv;
+ 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)
+ */
+ pr_info("Starting ring buffer hammer\n");
+ do_gettimeofday(&start_tv);
+ do {
+ struct ring_buffer_event *event;
+ int *entry;
+
+ 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);
+ }
+ do_gettimeofday(&end_tv);
+
+ if (consumer && !(++cnt % wakeup_interval))
+ wake_up_process(consumer);
+
+ } while (end_tv.tv_sec < (start_tv.tv_sec + RUN_TIME) && !kill_test);
+ pr_info("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;
+ /* finish var visible before waking up the consumer */
+ smp_wmb();
+ wake_up_process(consumer);
+ wait_for_completion(&read_done);
+ }
+
+ time = end_tv.tv_sec - start_tv.tv_sec;
+ time *= 1000000;
+ time += (long long)((long)end_tv.tv_usec - (long)start_tv.tv_usec);
+
+ entries = ring_buffer_entries(buffer);
+ overruns = ring_buffer_overruns(buffer);
+
+ if (kill_test)
+ pr_info("ERROR!\n");
+ pr_info("Time: %lld (usecs)\n", time);
+ pr_info("Overruns: %lld\n", overruns);
+ if (disable_reader)
+ pr_info("Read: (reader disabled)\n");
+ else
+ pr_info("Read: %ld (by %s)\n", read,
+ read_events ? "events" : "pages");
+ pr_info("Entries: %lld\n", entries);
+ pr_info("Total: %lld\n", entries + overruns + read);
+ pr_info("Missed: %ld\n", missed);
+ pr_info("Hit: %ld\n", hit);
+
+ do_div(time, 1000);
+ if (time)
+ hit /= (long)time;
+ else
+ pr_info("TIME IS ZERO??\n");
+
+ pr_info("Entries per millisec: %ld\n", hit);
+
+ if (hit) {
+ avg = 1000000 / hit;
+ pr_info("%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 (!kthread_should_stop() && !kill_test) {
+ complete(&read_start);
+
+ ring_buffer_consumer();
+
+ set_current_state(TASK_INTERRUPTIBLE);
+ if (kthread_should_stop() || kill_test)
+ break;
+
+ schedule();
+ __set_current_state(TASK_RUNNING);
+ }
+ __set_current_state(TASK_RUNNING);
+
+ if (kill_test)
+ wait_to_die();
+
+ return 0;
+}
+
+static int ring_buffer_producer_thread(void *arg)
+{
+ init_completion(&read_start);
+
+ while (!kthread_should_stop() && !kill_test) {
+ ring_buffer_reset(buffer);
+
+ if (consumer) {
+ smp_wmb();
+ wake_up_process(consumer);
+ wait_for_completion(&read_start);
+ }
+
+ ring_buffer_producer();
+
+ pr_info("Sleeping for 10 secs\n");
+ set_current_state(TASK_INTERRUPTIBLE);
+ schedule_timeout(HZ * SLEEP_TIME);
+ __set_current_state(TASK_RUNNING);
+ }
+
+ if (kill_test)
+ 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;
+
+ 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");
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