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Subject[PATCH v2 7/8] ring-buffer: Micro-optimize with some strategic inlining
From: Steven Rostedt <srostedt@redhat.com>

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@goodmis.org>
---
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 d9f3e7a..f5007d0 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -2078,7 +2078,7 @@ 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;

@@ -2193,13 +2193,9 @@ 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();

@@ -2211,10 +2207,21 @@ 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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