ring-buffer: small optimizations

Doing some small changes in the fast path of the ring buffer recording
saves over 3% in the ring-buffer-benchmark test.

[ Impact: a little faster ring buffer recording ]

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 493cba4..f452de2 100644 (file)
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -1000,7 +1000,7 @@ rb_event_index(struct ring_buffer_event *event)
        return (addr & ~PAGE_MASK) - (PAGE_SIZE - BUF_PAGE_SIZE);
 }
 
-static int
+static inline int
 rb_is_commit(struct ring_buffer_per_cpu *cpu_buffer,
             struct ring_buffer_event *event)
 {
@@ -1423,9 +1423,9 @@ rb_reserve_next_event(struct ring_buffer_per_cpu *cpu_buffer,
         * also be made. But only the entry that did the actual
         * commit will be something other than zero.
         */
-       if (cpu_buffer->tail_page == cpu_buffer->commit_page &&
-           rb_page_write(cpu_buffer->tail_page) ==
-           rb_commit_index(cpu_buffer)) {
+       if (likely(cpu_buffer->tail_page == cpu_buffer->commit_page &&
+                  rb_page_write(cpu_buffer->tail_page) ==
+                  rb_commit_index(cpu_buffer))) {
 
                delta = ts - cpu_buffer->write_stamp;
 
@@ -1436,7 +1436,7 @@ rb_reserve_next_event(struct ring_buffer_per_cpu *cpu_buffer,
                if (unlikely(ts < cpu_buffer->write_stamp))
                        delta = 0;
 
-               if (test_time_stamp(delta)) {
+               else if (unlikely(test_time_stamp(delta))) {
 
                        commit = rb_add_time_stamp(cpu_buffer, &ts, &delta);
 
@@ -1470,7 +1470,7 @@ rb_reserve_next_event(struct ring_buffer_per_cpu *cpu_buffer,
         * If the timestamp was commited, make the commit our entry
         * now so that we will update it when needed.
         */
-       if (commit)
+       if (unlikely(commit))
                rb_set_commit_event(cpu_buffer, event);
        else if (!rb_is_commit(cpu_buffer, event))
                delta = 0;