[PATCH v4 1/3] mempool: split stats from debug

["Morten Brørup" <mb@smartsharesystems.com>]

Split stats from debug, to make mempool statistics available without the
performance cost of continuously validating the debug cookies in the
mempool elements.

mempool_perf_autotest shows the following improvements in rate_persec.

The cost of enabling mempool debug without this patch:
-28.1 % and -74.0 %, respectively without and with cache.

The cost of enabling mempool stats (without debug) after this patch:
-5.8 % and -21.2 %, respectively without and with cache.

v4:
* No changes.
v3:
* Update the Programmer's Guide.
* Update the description of the RTE_MEMPOOL_STAT_ADD macro.
v2:
* Fix checkpatch warning:
  Use C style comments in rte_include.h, not C++ style.
* Do not rename the rte_mempool_debug_stats structure.

Signed-off-by: Morten Brørup <mb@smartsharesystems.com>
---
 config/rte_config.h                   |  2 ++
 doc/guides/prog_guide/mempool_lib.rst |  6 +++++-
 lib/mempool/rte_mempool.c             |  6 +++---
 lib/mempool/rte_mempool.h             | 11 ++++++-----
 4 files changed, 16 insertions(+), 9 deletions(-)

diff --git a/config/rte_config.h b/config/rte_config.h
index ae56a86394..3c4876d434 100644
--- a/config/rte_config.h
+++ b/config/rte_config.h
@@ -47,6 +47,8 @@
 
 /* mempool defines */
 #define RTE_MEMPOOL_CACHE_MAX_SIZE 512
+/* RTE_LIBRTE_MEMPOOL_STATS is not set */
+/* RTE_LIBRTE_MEMPOOL_DEBUG is not set */
 
 /* mbuf defines */
 #define RTE_MBUF_DEFAULT_MEMPOOL_OPS "ring_mp_mc"
diff --git a/doc/guides/prog_guide/mempool_lib.rst b/doc/guides/prog_guide/mempool_lib.rst
index 55838317b9..4f4ee33463 100644
--- a/doc/guides/prog_guide/mempool_lib.rst
+++ b/doc/guides/prog_guide/mempool_lib.rst
@@ -20,12 +20,16 @@ Cookies
 In debug mode, cookies are added at the beginning and end of allocated blocks.
 The allocated objects then contain overwrite protection fields to help debugging buffer overflows.
 
+Debug mode is disabled by default, but can be enabled by setting ``RTE_LIBRTE_MEMPOOL_DEBUG`` in ``config/rte_config.h``.
+
 Stats
 -----
 
-In debug mode, statistics about get from/put in the pool are stored in the mempool structure.
+In stats mode, statistics about get from/put in the pool are stored in the mempool structure.
 Statistics are per-lcore to avoid concurrent access to statistics counters.
 
+Stats mode is disabled by default, but can be enabled by setting ``RTE_LIBRTE_MEMPOOL_STATS`` in ``config/rte_config.h``.
+
 Memory Alignment Constraints on x86 architecture
 ------------------------------------------------
 
diff --git a/lib/mempool/rte_mempool.c b/lib/mempool/rte_mempool.c
index 21c94a2b9f..62d1ce764e 100644
--- a/lib/mempool/rte_mempool.c
+++ b/lib/mempool/rte_mempool.c
@@ -818,7 +818,7 @@ rte_mempool_create_empty(const char *name, unsigned n, unsigned elt_size,
 			  RTE_CACHE_LINE_MASK) != 0);
 	RTE_BUILD_BUG_ON((sizeof(struct rte_mempool_cache) &
 			  RTE_CACHE_LINE_MASK) != 0);
-#ifdef RTE_LIBRTE_MEMPOOL_DEBUG
+#ifdef RTE_LIBRTE_MEMPOOL_STATS
 	RTE_BUILD_BUG_ON((sizeof(struct rte_mempool_debug_stats) &
 			  RTE_CACHE_LINE_MASK) != 0);
 	RTE_BUILD_BUG_ON((offsetof(struct rte_mempool, stats) &
@@ -1221,7 +1221,7 @@ rte_mempool_audit(struct rte_mempool *mp)
 void
 rte_mempool_dump(FILE *f, struct rte_mempool *mp)
 {
-#ifdef RTE_LIBRTE_MEMPOOL_DEBUG
+#ifdef RTE_LIBRTE_MEMPOOL_STATS
 	struct rte_mempool_info info;
 	struct rte_mempool_debug_stats sum;
 	unsigned lcore_id;
@@ -1269,7 +1269,7 @@ rte_mempool_dump(FILE *f, struct rte_mempool *mp)
 	fprintf(f, "  common_pool_count=%u\n", common_count);
 
 	/* sum and dump statistics */
-#ifdef RTE_LIBRTE_MEMPOOL_DEBUG
+#ifdef RTE_LIBRTE_MEMPOOL_STATS
 	rte_mempool_ops_get_info(mp, &info);
 	memset(&sum, 0, sizeof(sum));
 	for (lcore_id = 0; lcore_id < RTE_MAX_LCORE; lcore_id++) {
diff --git a/lib/mempool/rte_mempool.h b/lib/mempool/rte_mempool.h
index 3725a72951..d5f7ea99fa 100644
--- a/lib/mempool/rte_mempool.h
+++ b/lib/mempool/rte_mempool.h
@@ -56,7 +56,7 @@ extern "C" {
 #define RTE_MEMPOOL_HEADER_COOKIE2  0xf2eef2eedadd2e55ULL /**< Header cookie. */
 #define RTE_MEMPOOL_TRAILER_COOKIE  0xadd2e55badbadbadULL /**< Trailer cookie.*/
 
-#ifdef RTE_LIBRTE_MEMPOOL_DEBUG
+#ifdef RTE_LIBRTE_MEMPOOL_STATS
 /**
  * A structure that stores the mempool statistics (per-lcore).
  * Note: Cache stats (put_cache_bulk/objs, get_cache_bulk/objs) are not
@@ -237,7 +237,7 @@ struct rte_mempool {
 	uint32_t nb_mem_chunks;          /**< Number of memory chunks */
 	struct rte_mempool_memhdr_list mem_list; /**< List of memory chunks */
 
-#ifdef RTE_LIBRTE_MEMPOOL_DEBUG
+#ifdef RTE_LIBRTE_MEMPOOL_STATS
 	/** Per-lcore statistics. */
 	struct rte_mempool_debug_stats stats[RTE_MAX_LCORE];
 #endif
@@ -292,17 +292,18 @@ struct rte_mempool {
 	| RTE_MEMPOOL_F_SC_GET \
 	| RTE_MEMPOOL_F_NO_IOVA_CONTIG \
 	)
+
 /**
- * @internal When debug is enabled, store some statistics.
+ * @internal When stats is enabled, store some statistics.
  *
  * @param mp
  *   Pointer to the memory pool.
  * @param name
  *   Name of the statistics field to increment in the memory pool.
  * @param n
- *   Number to add to the object-oriented statistics.
+ *   Number to add to the statistics.
  */
-#ifdef RTE_LIBRTE_MEMPOOL_DEBUG
+#ifdef RTE_LIBRTE_MEMPOOL_STATS
 #define RTE_MEMPOOL_STAT_ADD(mp, name, n) do {                  \
 		unsigned __lcore_id = rte_lcore_id();           \
 		if (__lcore_id < RTE_MAX_LCORE) {               \
-- 
2.17.1