[PATCH v2 04/14] soundwire: optimize sdw_bus structure

[Bard Liao]

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

The sdw_bus structure has seen multiple additions over the years. It's
one of the most used structures in this subsystem, so there's merit in
reshuffling the members a bit with 'pahole' to reduce holes and
structures across cache lines.

before:

struct sdw_bus {
	struct device *            dev;                  /*     0     8 */
	struct sdw_master_device * md;                   /*     8     8 */
	int                        controller_id;        /*    16     4 */
	unsigned int               link_id;              /*    20     4 */
	int                        id;                   /*    24     4 */

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

	struct list_head           slaves;               /*    32    16 */
	long unsigned int          assigned[1];          /*    48     8 */
	struct mutex               bus_lock;             /*    56   160 */
	/* --- cacheline 3 boundary (192 bytes) was 24 bytes ago --- */
	struct lock_class_key      bus_lock_key;         /*   216    16 */
	struct mutex               msg_lock;             /*   232   160 */
	/* --- cacheline 6 boundary (384 bytes) was 8 bytes ago --- */
	struct lock_class_key      msg_lock_key;         /*   392    16 */
	int                        (*compute_params)(struct sdw_bus *); /*   408     8 */
	const struct sdw_master_ops  * ops;              /*   416     8 */
	const struct sdw_master_port_ops  * port_ops;    /*   424     8 */
	struct sdw_bus_params      params;               /*   432    36 */

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

	/* --- cacheline 7 boundary (448 bytes) was 24 bytes ago --- */
	struct sdw_master_prop     prop;                 /*   472    72 */

	/* XXX last struct has 6 bytes of padding */

	/* --- cacheline 8 boundary (512 bytes) was 32 bytes ago --- */
	void *                     vendor_specific_prop; /*   544     8 */
	struct list_head           m_rt_list;            /*   552    16 */
	struct dentry *            debugfs;              /*   568     8 */
	/* --- cacheline 9 boundary (576 bytes) --- */
	struct irq_chip            irq_chip;             /*   576   264 */
	/* --- cacheline 13 boundary (832 bytes) was 8 bytes ago --- */
	struct irq_domain *        domain;               /*   840     8 */
	struct sdw_defer           defer_msg;            /*   848   112 */
	/* --- cacheline 15 boundary (960 bytes) --- */
	unsigned int               clk_stop_timeout;     /*   960     4 */
	u32                        bank_switch_timeout;  /*   964     4 */
	bool                       multi_link;           /*   968     1 */

	/* XXX 3 bytes hole, try to pack */

	int                        hw_sync_min_links;    /*   972     4 */
	int                        stream_refcount;      /*   976     4 */

	/* size: 984, cachelines: 16, members: 27 */
	/* sum members: 969, holes: 3, sum holes: 11 */
	/* padding: 4 */
	/* paddings: 1, sum paddings: 6 */
	/* last cacheline: 24 bytes */
};

after:

struct sdw_bus {
	struct device *            dev;                  /*     0     8 */
	struct sdw_master_device * md;                   /*     8     8 */
	struct lock_class_key      bus_lock_key;         /*    16    16 */
	struct mutex               bus_lock;             /*    32   160 */
	/* --- cacheline 3 boundary (192 bytes) --- */
	struct list_head           slaves;               /*   192    16 */
	struct lock_class_key      msg_lock_key;         /*   208    16 */
	struct mutex               msg_lock;             /*   224   160 */
	/* --- cacheline 6 boundary (384 bytes) --- */
	struct list_head           m_rt_list;            /*   384    16 */
	struct sdw_defer           defer_msg;            /*   400   112 */
	/* --- cacheline 8 boundary (512 bytes) --- */
	struct sdw_bus_params      params;               /*   512    36 */
	int                        stream_refcount;      /*   548     4 */
	const struct sdw_master_ops  * ops;              /*   552     8 */
	const struct sdw_master_port_ops  * port_ops;    /*   560     8 */
	struct sdw_master_prop     prop;                 /*   568    72 */

	/* XXX last struct has 6 bytes of padding */

	/* --- cacheline 10 boundary (640 bytes) --- */
	void *                     vendor_specific_prop; /*   640     8 */
	int                        hw_sync_min_links;    /*   648     4 */
	int                        controller_id;        /*   652     4 */
	unsigned int               link_id;              /*   656     4 */
	int                        id;                   /*   660     4 */
	int                        (*compute_params)(struct sdw_bus *); /*   664     8 */
	long unsigned int          assigned[1];          /*   672     8 */
	unsigned int               clk_stop_timeout;     /*   680     4 */
	u32                        bank_switch_timeout;  /*   684     4 */
	struct irq_chip            irq_chip;             /*   688   264 */
	/* --- cacheline 14 boundary (896 bytes) was 56 bytes ago --- */
	struct irq_domain *        domain;               /*   952     8 */
	/* --- cacheline 15 boundary (960 bytes) --- */
	struct dentry *            debugfs;              /*   960     8 */
	bool                       multi_link;           /*   968     1 */

	/* size: 976, cachelines: 16, members: 27 */
	/* padding: 7 */
	/* paddings: 1, sum paddings: 6 */
	/* last cacheline: 16 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 | 79 ++++++++++++++++++-----------------
 1 file changed, 41 insertions(+), 38 deletions(-)

diff --git a/include/linux/soundwire/sdw.h b/include/linux/soundwire/sdw.h
index 2caea7345c3e..6fcf122c1831 100644
--- a/include/linux/soundwire/sdw.h
+++ b/include/linux/soundwire/sdw.h
@@ -871,68 +871,71 @@ struct sdw_master_ops {
  * struct sdw_bus - SoundWire bus
  * @dev: Shortcut to &bus->md->dev to avoid changing the entire code.
  * @md: Master device
- * @controller_id: system-unique controller ID. If set to -1, the bus @id will be used.
- * @link_id: Link id number, can be 0 to N, unique for each Controller
- * @id: bus system-wide unique id
- * @slaves: list of Slaves on this bus
- * @assigned: Bitmap for Slave device numbers.
- * Bit set implies used number, bit clear implies unused number.
+ * @bus_lock_key: bus lock key associated to @bus_lock
  * @bus_lock: bus lock
+ * @slaves: list of Slaves on this bus
+ * @msg_lock_key: message lock key associated to @msg_lock
  * @msg_lock: message lock
- * @compute_params: points to Bus resource management implementation
- * @ops: Master callback ops
- * @port_ops: Master port callback ops
- * @params: Current bus parameters
- * @prop: Master properties
- * @vendor_specific_prop: pointer to non-standard properties
  * @m_rt_list: List of Master instance of all stream(s) running on Bus. This
  * is used to compute and program bus bandwidth, clock, frame shape,
  * transport and port parameters
- * @debugfs: Bus debugfs
- * @domain: IRQ domain
  * @defer_msg: Defer message
- * @clk_stop_timeout: Clock stop timeout computed
- * @bank_switch_timeout: Bank switch timeout computed
- * @multi_link: Store bus property that indicates if multi links
- * are supported. This flag is populated by drivers after reading
- * appropriate firmware (ACPI/DT).
+ * @params: Current bus parameters
+ * @stream_refcount: number of streams currently using this bus
+ * @ops: Master callback ops
+ * @port_ops: Master port callback ops
+ * @prop: Master properties
+ * @vendor_specific_prop: pointer to non-standard properties
  * @hw_sync_min_links: Number of links used by a stream above which
  * hardware-based synchronization is required. This value is only
  * meaningful if multi_link is set. If set to 1, hardware-based
  * synchronization will be used even if a stream only uses a single
  * SoundWire segment.
- * @stream_refcount: number of streams currently using this bus
+ * @controller_id: system-unique controller ID. If set to -1, the bus @id will be used.
+ * @link_id: Link id number, can be 0 to N, unique for each Controller
+ * @id: bus system-wide unique id
+ * @compute_params: points to Bus resource management implementation
+ * @assigned: Bitmap for Slave device numbers.
+ * Bit set implies used number, bit clear implies unused number.
+ * @clk_stop_timeout: Clock stop timeout computed
+ * @bank_switch_timeout: Bank switch timeout computed
+ * @domain: IRQ domain
+ * @irq_chip: IRQ chip
+ * @debugfs: Bus debugfs (optional)
+ * @multi_link: Store bus property that indicates if multi links
+ * are supported. This flag is populated by drivers after reading
+ * appropriate firmware (ACPI/DT).
  */
 struct sdw_bus {
 	struct device *dev;
 	struct sdw_master_device *md;
-	int controller_id;
-	unsigned int link_id;
-	int id;
-	struct list_head slaves;
-	DECLARE_BITMAP(assigned, SDW_MAX_DEVICES);
-	struct mutex bus_lock;
 	struct lock_class_key bus_lock_key;
-	struct mutex msg_lock;
+	struct mutex bus_lock;
+	struct list_head slaves;
 	struct lock_class_key msg_lock_key;
-	int (*compute_params)(struct sdw_bus *bus);
+	struct mutex msg_lock;
+	struct list_head m_rt_list;
+	struct sdw_defer defer_msg;
+	struct sdw_bus_params params;
+	int stream_refcount;
 	const struct sdw_master_ops *ops;
 	const struct sdw_master_port_ops *port_ops;
-	struct sdw_bus_params params;
 	struct sdw_master_prop prop;
 	void *vendor_specific_prop;
-	struct list_head m_rt_list;
-#ifdef CONFIG_DEBUG_FS
-	struct dentry *debugfs;
-#endif
-	struct irq_chip irq_chip;
-	struct irq_domain *domain;
-	struct sdw_defer defer_msg;
+	int hw_sync_min_links;
+	int controller_id;
+	unsigned int link_id;
+	int id;
+	int (*compute_params)(struct sdw_bus *bus);
+	DECLARE_BITMAP(assigned, SDW_MAX_DEVICES);
 	unsigned int clk_stop_timeout;
 	u32 bank_switch_timeout;
+	struct irq_chip irq_chip;
+	struct irq_domain *domain;
+#ifdef CONFIG_DEBUG_FS
+	struct dentry *debugfs;
+#endif
 	bool multi_link;
-	int hw_sync_min_links;
-	int stream_refcount;
 };
 
 int sdw_bus_master_add(struct sdw_bus *bus, struct device *parent,
-- 
2.43.0