[dpdk-dev] [PATCH v3 01/14] ring: remove split cacheline build setting

[Bruce Richardson <bruce.richardson@intel.com>]

Users compiling DPDK should not need to know or care about the arrangement
of cachelines in the rte_ring structure.  Therefore just remove the build
option and set the structures to be always split. On platforms with 64B
cachelines, for improved performance use 128B rather than 64B alignment
since it stops the producer and consumer data being on adjacent cachelines.

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
Acked-by: Olivier Matz <olivier.matz@6wind.com>
---
V2: Limit the cacheline * 2 alignment to platforms with < 128B line size
---
 config/common_base                     |  1 -
 doc/guides/rel_notes/release_17_05.rst |  7 +++++++
 lib/librte_ring/rte_ring.c             |  2 --
 lib/librte_ring/rte_ring.h             | 16 ++++++++++------
 4 files changed, 17 insertions(+), 9 deletions(-)

diff --git a/config/common_base b/config/common_base
index 37aa1e1..c394651 100644
--- a/config/common_base
+++ b/config/common_base
@@ -453,7 +453,6 @@ CONFIG_RTE_LIBRTE_PMD_NULL_CRYPTO=y
 #
 CONFIG_RTE_LIBRTE_RING=y
 CONFIG_RTE_LIBRTE_RING_DEBUG=n
-CONFIG_RTE_RING_SPLIT_PROD_CONS=n
 CONFIG_RTE_RING_PAUSE_REP_COUNT=0
 
 #
diff --git a/doc/guides/rel_notes/release_17_05.rst b/doc/guides/rel_notes/release_17_05.rst
index 918f483..57ae8bf 100644
--- a/doc/guides/rel_notes/release_17_05.rst
+++ b/doc/guides/rel_notes/release_17_05.rst
@@ -120,6 +120,13 @@ API Changes
 * The LPM ``next_hop`` field is extended from 8 bits to 21 bits for IPv6
   while keeping ABI compatibility.
 
+* **Reworked rte_ring library**
+
+  The rte_ring library has been reworked and updated. The following changes
+  have been made to it:
+
+  * removed the build-time setting ``CONFIG_RTE_RING_SPLIT_PROD_CONS``
+
 ABI Changes
 -----------
 
diff --git a/lib/librte_ring/rte_ring.c b/lib/librte_ring/rte_ring.c
index ca0a108..4bc6da1 100644
--- a/lib/librte_ring/rte_ring.c
+++ b/lib/librte_ring/rte_ring.c
@@ -127,10 +127,8 @@ rte_ring_init(struct rte_ring *r, const char *name, unsigned count,
 	/* compilation-time checks */
 	RTE_BUILD_BUG_ON((sizeof(struct rte_ring) &
 			  RTE_CACHE_LINE_MASK) != 0);
-#ifdef RTE_RING_SPLIT_PROD_CONS
 	RTE_BUILD_BUG_ON((offsetof(struct rte_ring, cons) &
 			  RTE_CACHE_LINE_MASK) != 0);
-#endif
 	RTE_BUILD_BUG_ON((offsetof(struct rte_ring, prod) &
 			  RTE_CACHE_LINE_MASK) != 0);
 #ifdef RTE_LIBRTE_RING_DEBUG
diff --git a/lib/librte_ring/rte_ring.h b/lib/librte_ring/rte_ring.h
index 72ccca5..399ae3b 100644
--- a/lib/librte_ring/rte_ring.h
+++ b/lib/librte_ring/rte_ring.h
@@ -139,6 +139,14 @@ struct rte_ring_debug_stats {
 
 struct rte_memzone; /* forward declaration, so as not to require memzone.h */
 
+#if RTE_CACHE_LINE_SIZE < 128
+#define PROD_ALIGN (RTE_CACHE_LINE_SIZE * 2)
+#define CONS_ALIGN (RTE_CACHE_LINE_SIZE * 2)
+#else
+#define PROD_ALIGN RTE_CACHE_LINE_SIZE
+#define CONS_ALIGN RTE_CACHE_LINE_SIZE
+#endif
+
 /**
  * An RTE ring structure.
  *
@@ -168,7 +176,7 @@ struct rte_ring {
 		uint32_t mask;           /**< Mask (size-1) of ring. */
 		volatile uint32_t head;  /**< Producer head. */
 		volatile uint32_t tail;  /**< Producer tail. */
-	} prod __rte_cache_aligned;
+	} prod __rte_aligned(PROD_ALIGN);
 
 	/** Ring consumer status. */
 	struct cons {
@@ -177,11 +185,7 @@ struct rte_ring {
 		uint32_t mask;           /**< Mask (size-1) of ring. */
 		volatile uint32_t head;  /**< Consumer head. */
 		volatile uint32_t tail;  /**< Consumer tail. */
-#ifdef RTE_RING_SPLIT_PROD_CONS
-	} cons __rte_cache_aligned;
-#else
-	} cons;
-#endif
+	} cons __rte_aligned(CONS_ALIGN);
 
 #ifdef RTE_LIBRTE_RING_DEBUG
 	struct rte_ring_debug_stats stats[RTE_MAX_LCORE];
-- 
2.9.3