[PATCH] mempool: test performance with constant n

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

"What gets measured gets done."

This patch adds mempool performance tests where the number of objects to
put and get is constant at compile time, which may significantly improve
the performance of these functions. [*]

Also, it is ensured that the array holding the object used for testing
is cache line aligned, for maximum performance.

And finally, the following entries are added to the list of tests:
- Number of kept objects: 512
- Number of objects to get and to put: The number of pointers fitting
  into a cache line, i.e. 8 or 16

[*] Some example performance test (with cache) results:

get_bulk=4 put_bulk=4 keep=128 constant_n=false rate_persec=280480972
get_bulk=4 put_bulk=4 keep=128 constant_n=true  rate_persec=622159462

get_bulk=8 put_bulk=8 keep=128 constant_n=false rate_persec=477967155
get_bulk=8 put_bulk=8 keep=128 constant_n=true  rate_persec=917582643

get_bulk=32 put_bulk=32 keep=32 constant_n=false rate_persec=871248691
get_bulk=32 put_bulk=32 keep=32 constant_n=true rate_persec=1134021836

Signed-off-by: Morten Brørup <mb@smartsharesystems.com>
---
 app/test/test_mempool_perf.c | 120 +++++++++++++++++++++--------------
 1 file changed, 74 insertions(+), 46 deletions(-)

diff --git a/app/test/test_mempool_perf.c b/app/test/test_mempool_perf.c
index 87ad251367..ffefe934d5 100644
--- a/app/test/test_mempool_perf.c
+++ b/app/test/test_mempool_perf.c
@@ -1,5 +1,6 @@
 /* SPDX-License-Identifier: BSD-3-Clause
  * Copyright(c) 2010-2014 Intel Corporation
+ * Copyright(c) 2022 SmartShare Systems
  */
 
 #include <string.h>
@@ -55,19 +56,24 @@
  *
  *      - Bulk get from 1 to 32
  *      - Bulk put from 1 to 32
+ *      - Bulk get and put from 1 to 32, compile time constant
  *
  *    - Number of kept objects (*n_keep*)
  *
  *      - 32
  *      - 128
+ *      - 512
  */
 
 #define N 65536
 #define TIME_S 5
 #define MEMPOOL_ELT_SIZE 2048
-#define MAX_KEEP 128
+#define MAX_KEEP 512
 #define MEMPOOL_SIZE ((rte_lcore_count()*(MAX_KEEP+RTE_MEMPOOL_CACHE_MAX_SIZE))-1)
 
+/* Number of pointers fitting into one cache line. */
+#define CACHE_LINE_BURST (RTE_CACHE_LINE_SIZE/sizeof(uintptr_t))
+
 #define LOG_ERR() printf("test failed at %s():%d\n", __func__, __LINE__)
 #define RET_ERR() do {							\
 		LOG_ERR();						\
@@ -80,16 +86,16 @@
 	} while (0)
 
 static int use_external_cache;
-static unsigned external_cache_size = RTE_MEMPOOL_CACHE_MAX_SIZE;
+static unsigned int external_cache_size = RTE_MEMPOOL_CACHE_MAX_SIZE;
 
 static uint32_t synchro;
 
 /* number of objects in one bulk operation (get or put) */
-static unsigned n_get_bulk;
-static unsigned n_put_bulk;
+static int n_get_bulk;
+static int n_put_bulk;
 
 /* number of objects retrieved from mempool before putting them back */
-static unsigned n_keep;
+static int n_keep;
 
 /* number of enqueues / dequeues */
 struct mempool_test_stats {
@@ -104,20 +110,43 @@ static struct mempool_test_stats stats[RTE_MAX_LCORE];
  */
 static void
 my_obj_init(struct rte_mempool *mp, __rte_unused void *arg,
-	    void *obj, unsigned i)
+	    void *obj, unsigned int i)
 {
 	uint32_t *objnum = obj;
 	memset(obj, 0, mp->elt_size);
 	*objnum = i;
 }
 
+#define test_loop(x_keep, x_get_bulk, x_put_bulk)		       \
+		for (i = 0; likely(i < (N/x_keep)); i++) {	      \
+			/* get x_keep objects by bulk of x_get_bulk */  \
+			for (idx = 0; idx < x_keep; idx += x_get_bulk) {\
+				ret = rte_mempool_generic_get(mp,       \
+						&obj_table[idx],	\
+						x_get_bulk,	     \
+						cache);		 \
+				if (unlikely(ret < 0)) {		\
+					rte_mempool_dump(stdout, mp);   \
+					GOTO_ERR(ret, out);	     \
+				}				       \
+			}					       \
+									\
+			/* put the objects back by bulk of x_put_bulk */\
+			for (idx = 0; idx < x_keep; idx += x_put_bulk) {\
+				rte_mempool_generic_put(mp,	     \
+						&obj_table[idx],	\
+						x_put_bulk,	     \
+						cache);		 \
+			}					       \
+		}
+
 static int
 per_lcore_mempool_test(void *arg)
 {
-	void *obj_table[MAX_KEEP];
-	unsigned i, idx;
+	void *obj_table[MAX_KEEP] __rte_cache_aligned;
+	int i, idx;
 	struct rte_mempool *mp = arg;
-	unsigned lcore_id = rte_lcore_id();
+	unsigned int lcore_id = rte_lcore_id();
 	int ret = 0;
 	uint64_t start_cycles, end_cycles;
 	uint64_t time_diff = 0, hz = rte_get_timer_hz();
@@ -139,6 +168,9 @@ per_lcore_mempool_test(void *arg)
 		GOTO_ERR(ret, out);
 	if (((n_keep / n_put_bulk) * n_put_bulk) != n_keep)
 		GOTO_ERR(ret, out);
+	/* for constant n, n_get_bulk and n_put_bulk must be the same */
+	if (n_get_bulk < 0 && n_put_bulk != n_get_bulk)
+		GOTO_ERR(ret, out);
 
 	stats[lcore_id].enq_count = 0;
 
@@ -149,30 +181,18 @@ per_lcore_mempool_test(void *arg)
 	start_cycles = rte_get_timer_cycles();
 
 	while (time_diff/hz < TIME_S) {
-		for (i = 0; likely(i < (N/n_keep)); i++) {
-			/* get n_keep objects by bulk of n_bulk */
-			idx = 0;
-			while (idx < n_keep) {
-				ret = rte_mempool_generic_get(mp,
-							      &obj_table[idx],
-							      n_get_bulk,
-							      cache);
-				if (unlikely(ret < 0)) {
-					rte_mempool_dump(stdout, mp);
-					/* in this case, objects are lost... */
-					GOTO_ERR(ret, out);
-				}
-				idx += n_get_bulk;
-			}
-
-			/* put the objects back */
-			idx = 0;
-			while (idx < n_keep) {
-				rte_mempool_generic_put(mp, &obj_table[idx],
-							n_put_bulk,
-							cache);
-				idx += n_put_bulk;
-			}
+		if (n_get_bulk > 0) {
+			test_loop(n_keep, n_get_bulk, n_put_bulk);
+		} else if (n_get_bulk == -1) {
+			test_loop(-n_keep, 1, 1);
+		} else if (n_get_bulk == -4) {
+			test_loop(-n_keep, 4, 4);
+		} else if (n_get_bulk == -(int)CACHE_LINE_BURST) {
+			test_loop(-n_keep, CACHE_LINE_BURST, CACHE_LINE_BURST);
+		} else if (n_get_bulk == -32) {
+			test_loop(-n_keep, 32, 32);
+		} else {
+			GOTO_ERR(ret, out);
 		}
 		end_cycles = rte_get_timer_cycles();
 		time_diff = end_cycles - start_cycles;
@@ -192,10 +212,10 @@ per_lcore_mempool_test(void *arg)
 static int
 launch_cores(struct rte_mempool *mp, unsigned int cores)
 {
-	unsigned lcore_id;
+	unsigned int lcore_id;
 	uint64_t rate;
 	int ret;
-	unsigned cores_save = cores;
+	unsigned int cores_save = cores;
 
 	__atomic_store_n(&synchro, 0, __ATOMIC_RELAXED);
 
@@ -203,10 +223,14 @@ launch_cores(struct rte_mempool *mp, unsigned int cores)
 	memset(stats, 0, sizeof(stats));
 
 	printf("mempool_autotest cache=%u cores=%u n_get_bulk=%u "
-	       "n_put_bulk=%u n_keep=%u ",
+	       "n_put_bulk=%u n_keep=%u constant_n=%s ",
 	       use_external_cache ?
-		   external_cache_size : (unsigned) mp->cache_size,
-	       cores, n_get_bulk, n_put_bulk, n_keep);
+		   external_cache_size : (unsigned int) mp->cache_size,
+	       cores,
+	       n_get_bulk > 0 ? n_get_bulk : -n_get_bulk,
+	       n_put_bulk > 0 ? n_put_bulk : -n_put_bulk,
+	       n_keep > 0 ? n_keep : -n_keep,
+	       n_get_bulk > 0 ? "false" : "true");
 
 	if (rte_mempool_avail_count(mp) != MEMPOOL_SIZE) {
 		printf("mempool is not full\n");
@@ -253,12 +277,13 @@ launch_cores(struct rte_mempool *mp, unsigned int cores)
 static int
 do_one_mempool_test(struct rte_mempool *mp, unsigned int cores)
 {
-	unsigned bulk_tab_get[] = { 1, 4, 32, 0 };
-	unsigned bulk_tab_put[] = { 1, 4, 32, 0 };
-	unsigned keep_tab[] = { 32, 128, 0 };
-	unsigned *get_bulk_ptr;
-	unsigned *put_bulk_ptr;
-	unsigned *keep_ptr;
+	/* Negative n_get_bulk values represent constants in the test. */
+	int bulk_tab_get[] = { 1, 4, CACHE_LINE_BURST, 32, -1, -4, -(int)CACHE_LINE_BURST, -32, 0 };
+	int bulk_tab_put[] = { 1, 4, CACHE_LINE_BURST, 32, 0 };
+	int keep_tab[] = { 32, 128, 512, 0 };
+	int *get_bulk_ptr;
+	int *put_bulk_ptr;
+	int *keep_ptr;
 	int ret;
 
 	for (get_bulk_ptr = bulk_tab_get; *get_bulk_ptr; get_bulk_ptr++) {
@@ -266,13 +291,16 @@ do_one_mempool_test(struct rte_mempool *mp, unsigned int cores)
 			for (keep_ptr = keep_tab; *keep_ptr; keep_ptr++) {
 
 				n_get_bulk = *get_bulk_ptr;
-				n_put_bulk = *put_bulk_ptr;
-				n_keep = *keep_ptr;
+				n_put_bulk = n_get_bulk > 0 ? *put_bulk_ptr : n_get_bulk;
+				n_keep = n_get_bulk > 0 ? *keep_ptr : -*keep_ptr;
 				ret = launch_cores(mp, cores);
 
 				if (ret < 0)
 					return -1;
 			}
+			/* Skip the put loop when n is constant */
+			if (n_get_bulk < 0)
+				break;
 		}
 	}
 	return 0;
-- 
2.17.1