[PATCH 4/5] ring-buffer: Micro-optimize with some strategic inlining

[Steven Rostedt]

From: Steven Rostedt <srostedt@xxxxxxxxxx>

By using inline and noinline, we are able to make the fast path of
recording an event 4% faster.

Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
---
 kernel/trace/ring_buffer.c |   23 +++++++++++++++--------
 1 files changed, 15 insertions(+), 8 deletions(-)

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 9f55330..fda009a 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -2085,7 +2085,7 @@ static void rb_start_commit(struct ring_buffer_per_cpu *cpu_buffer)
 	local_inc(&cpu_buffer->commits);
 }
 
-static void rb_end_commit(struct ring_buffer_per_cpu *cpu_buffer)
+static inline void rb_end_commit(struct ring_buffer_per_cpu *cpu_buffer)
 {
 	unsigned long commits;
 
@@ -2200,13 +2200,9 @@ rb_reserve_next_event(struct ring_buffer *buffer,
 
 #define TRACE_RECURSIVE_DEPTH 16
 
-static int trace_recursive_lock(void)
+/* Keep this code out of the fast path cache */
+static noinline void trace_recursive_fail(void)
 {
-	current->trace_recursion++;
-
-	if (likely(current->trace_recursion < TRACE_RECURSIVE_DEPTH))
-		return 0;
-
 	/* Disable all tracing before we do anything else */
 	tracing_off_permanent();
 
@@ -2218,10 +2214,21 @@ static int trace_recursive_lock(void)
 		    in_nmi());
 
 	WARN_ON_ONCE(1);
+}
+
+static inline int trace_recursive_lock(void)
+{
+	current->trace_recursion++;
+
+	if (likely(current->trace_recursion < TRACE_RECURSIVE_DEPTH))
+		return 0;
+
+	trace_recursive_fail();
+
 	return -1;
 }
 
-static void trace_recursive_unlock(void)
+static inline void trace_recursive_unlock(void)
 {
 	WARN_ON_ONCE(!current->trace_recursion);
 
-- 
1.7.1


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