ring-buffer: remove complex calculations in ring-buffer-test

Ingo Molnar thought that the code to calculate the time in cond_resched
is a bit too ugly and is not needed. This patch removes it and replaces
it with a simple call to cond_resched. I kept the comment that explains
the reason for the cond_resched.

[ Impact: remove ugly code ]

Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 7 insertions, 30 deletions

diff --git a/kernel/trace/ring_buffer_benchmark.c b/kernel/trace/ring_buffer_benchmark.c
index a26fc67b63bb..f4ceb453c7dd 100644
--- a/kernel/trace/ring_buffer_benchmark.c
+++ b/kernel/trace/ring_buffer_benchmark.c
@@ -185,35 +185,6 @@ static void ring_buffer_consumer(void)
         complete(&read_done);
 }
 
-/*
- * 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.
- */
-#ifdef CONFIG_PREEMPT
-static void sched_if_needed(struct timeval *start_tv, struct timeval *end_tv)
-{
-}
-#else
-static void sched_if_needed(struct timeval *start_tv, struct timeval *end_tv)
-{
-        struct timeval tv;
-
-        cond_resched();
-        do_gettimeofday(&tv);
-        if (tv.tv_usec < end_tv->tv_usec) {
-                tv.tv_usec += 1000000;
-                tv.tv_sec--;
-        }
-        start_tv->tv_sec += tv.tv_sec - end_tv->tv_sec;
-        start_tv->tv_usec += tv.tv_usec - end_tv->tv_usec;
-        if (start_tv->tv_usec > 1000000) {
-                start_tv->tv_usec -= 1000000;
-                start_tv->tv_sec++;
-        }
-}
-#endif
-
 static void ring_buffer_producer(void)
 {
         struct timeval start_tv;
@@ -250,7 +221,13 @@ static void ring_buffer_producer(void)
                 if (consumer && !(++cnt % wakeup_interval))
                         wake_up_process(consumer);
 
-                sched_if_needed(&start_tv, &end_tv);
+                /*
+                 * 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.
+                 */
+                cond_resched();
 
         } while (end_tv.tv_sec < (start_tv.tv_sec + RUN_TIME) && !kill_test);
         pr_info("End ring buffer hammer\n");