From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Sun, 25 Sep 2016 14:46:44 +0000 (-0400)
Subject: Performance: mark ring buffer do_copy callers always inline
X-Git-Tag: v2.9.0-rc1~15
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=d723e9056812fdee222f1156f45f7a43393c5863;p=lttng-modules.git

Performance: mark ring buffer do_copy callers always inline

The underlying copy operation is more efficient if the size is a
constant, which only happens if this function is inlined in the caller.
Otherwise, we end up calling memcpy for each field.

Force inlining for performance reasons for:
  - lib_ring_buffer_do_strcpy,
  - lib_ring_buffer_do_strcpy_from_user_inatomic,
  - lib_ring_buffer_copy_from_user_inatomic.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
---

diff --git a/lib/ringbuffer/backend.h b/lib/ringbuffer/backend.h
index 449d6635..b362a04a 100644
--- a/lib/ringbuffer/backend.h
+++ b/lib/ringbuffer/backend.h
@@ -168,7 +168,7 @@ void lib_ring_buffer_memset(const struct lib_ring_buffer_config *config,
  * terminating character is found in @src. Returns the number of bytes
  * copied. Does *not* terminate @dest with NULL terminating character.
  */
-static inline
+static inline __attribute__((always_inline))
 size_t lib_ring_buffer_do_strcpy(const struct lib_ring_buffer_config *config,
 		char *dest, const char *src, size_t len)
 {
@@ -199,7 +199,7 @@ size_t lib_ring_buffer_do_strcpy(const struct lib_ring_buffer_config *config,
  * directly without having the src pointer checked with access_ok()
  * previously.
  */
-static inline
+static inline __attribute__((always_inline))
 size_t lib_ring_buffer_do_strcpy_from_user_inatomic(const struct lib_ring_buffer_config *config,
 		char *dest, const char __user *src, size_t len)
 {
@@ -297,7 +297,7 @@ void lib_ring_buffer_strcpy(const struct lib_ring_buffer_config *config,
  * (_ring_buffer_write_from_user_inatomic) if copy is crossing a page boundary.
  * Disable the page fault handler to ensure we never try to take the mmap_sem.
  */
-static inline
+static inline __attribute__((always_inline))
 void lib_ring_buffer_copy_from_user_inatomic(const struct lib_ring_buffer_config *config,
 				    struct lib_ring_buffer_ctx *ctx,
 				    const void __user *src, size_t len)