svn commit: r277887 - head/sys/dev/sfxge

[Andrew Rybchenko]

Author: arybchik
Date: Thu Jan 29 18:57:27 2015
New Revision: 277887
URL: https://svnweb.freebsd.org/changeset/base/277887

Log:
  sfxge: Remove extra cache-line alignment and reorder sfxge_evq_t
  
  Remove the first member alignment to cacheline since it is nop.
  Use __aligned() for the whole structure to make sure that the structure
  size is cacheline aligned.
  Remove lock alignment to make the structure smaller and fit all members
  used on event queue processing into one cacheline (128 bytes) on x86-64.
  The lock is obtained as well from different context when event queue
  statistics are retrived from sysctl context, but it is infrequent.
  Reorder members to avoid padding and go in usage order on event
  processing.
  As the result all structure members used on event queue processing fit
  into exactly one cacheline (128 byte) now.
  
  Sponsored by:   Solarflare Communications, Inc.
  Approved by:    gnn (mentor)

Modified:
  head/sys/dev/sfxge/sfxge.h

Modified: head/sys/dev/sfxge/sfxge.h
==============================================================================
--- head/sys/dev/sfxge/sfxge.h	Thu Jan 29 18:54:43 2015	(r277886)
+++ head/sys/dev/sfxge/sfxge.h	Thu Jan 29 18:57:27 2015	(r277887)
@@ -103,26 +103,26 @@ enum sfxge_evq_state {
 #define	SFXGE_EV_BATCH	16384
 
 struct sfxge_evq {
-	struct sfxge_softc	*sc  __aligned(CACHE_LINE_SIZE);
-	struct mtx		lock __aligned(CACHE_LINE_SIZE);
-
-	enum sfxge_evq_state	init_state;
+	/* Structure members below are sorted by usage order */
+	struct sfxge_softc	*sc;
+	struct mtx		lock;
 	unsigned int		index;
-	unsigned int		entries;
+	enum sfxge_evq_state	init_state;
 	efsys_mem_t		mem;
-	unsigned int		buf_base_id;
-
-	boolean_t		exception;
-
 	efx_evq_t		*common;
 	unsigned int		read_ptr;
+	boolean_t		exception;
 	unsigned int		rx_done;
 	unsigned int		tx_done;
 
 	/* Linked list of TX queues with completions to process */
 	struct sfxge_txq	*txq;
 	struct sfxge_txq	**txqs;
-};
+
+	/* Structure members not used on event processing path */
+	unsigned int		buf_base_id;
+	unsigned int		entries;
+} __aligned(CACHE_LINE_SIZE);
 
 #define	SFXGE_NDESCS	1024
 #define	SFXGE_MODERATION	30