[PATCH v2 RESEND 02/14] soundwire: optimize sdw_stream_runtime memory layout

From: Bard Liao
Date: Thu Oct 03 2024 - 03:07:56 EST


From: Pierre-Louis Bossart <pierre-louis.bossart@xxxxxxxxxxxxxxx>

pahole suggestion: swap position of 'm_rt_count'

before: pahole -C sdw_stream_runtime drivers/soundwire/soundwire-bus.ko
struct sdw_stream_runtime {
const char * name; /* 0 8 */
struct sdw_stream_params params; /* 8 12 */
enum sdw_stream_state state; /* 20 4 */
enum sdw_stream_type type; /* 24 4 */

/* XXX 4 bytes hole, try to pack */

struct list_head master_list; /* 32 16 */
int m_rt_count; /* 48 4 */

/* size: 56, cachelines: 1, members: 6 */
/* sum members: 48, holes: 1, sum holes: 4 */
/* padding: 4 */
/* last cacheline: 56 bytes */
};

after: pahole --reorganize -C sdw_stream_runtime drivers/soundwire/soundwire-bus.ko
struct sdw_stream_runtime {
const char * name; /* 0 8 */
struct sdw_stream_params params; /* 8 12 */
enum sdw_stream_state state; /* 20 4 */
enum sdw_stream_type type; /* 24 4 */
int m_rt_count; /* 28 4 */
struct list_head master_list; /* 32 16 */

/* size: 48, cachelines: 1, members: 6 */
/* last cacheline: 48 bytes */
}; /* saved 8 bytes! */

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@xxxxxxxxxxxxxxx>
Signed-off-by: Bard Liao <yung-chuan.liao@xxxxxxxxxxxxxxx>
---
include/linux/soundwire/sdw.h | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/include/linux/soundwire/sdw.h b/include/linux/soundwire/sdw.h
index 5e0dd47a0412..a4fa45132030 100644
--- a/include/linux/soundwire/sdw.h
+++ b/include/linux/soundwire/sdw.h
@@ -820,15 +820,15 @@ struct sdw_master_port_ops {
struct sdw_msg;

/**
- * struct sdw_defer - SDW deffered message
- * @length: message length
+ * struct sdw_defer - SDW deferred message
* @complete: message completion
* @msg: SDW message
+ * @length: message length
*/
struct sdw_defer {
+ struct sdw_msg *msg;
int length;
struct completion complete;
- struct sdw_msg *msg;
};

/**
@@ -1010,18 +1010,18 @@ struct sdw_stream_params {
* @params: Stream parameters
* @state: Current state of the stream
* @type: Stream type PCM or PDM
+ * @m_rt_count: Count of Master runtime(s) in this stream
* @master_list: List of Master runtime(s) in this stream.
* master_list can contain only one m_rt per Master instance
* for a stream
- * @m_rt_count: Count of Master runtime(s) in this stream
*/
struct sdw_stream_runtime {
const char *name;
struct sdw_stream_params params;
enum sdw_stream_state state;
enum sdw_stream_type type;
- struct list_head master_list;
int m_rt_count;
+ struct list_head master_list;
};

struct sdw_stream_runtime *sdw_alloc_stream(const char *stream_name);
--
2.43.0