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
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