[dpdk-dev] [PATCH v3] kni: use bulk functions to allocate and free mbufs

[Sergey Vyazmitinov <s.vyazmitinov@brain4net.com>]

Optimized kni_allocate_mbufs and kni_free_mbufs by using mbuf bulk
functions. This can improve performance more than two times.

Signed-off-by: Sergey Vyazmitinov <s.vyazmitinov@brain4net.com>
---
v2:
* CSG fixes.
v3:
* Fixed issue with possible different mempools in buffer list.
* Fixed issue with wrong rte_pktmbuf_alloc_bulk function return value
processing in the kni_allocate_mbufs.
---
 lib/librte_kni/rte_kni.c      | 46 +++++++++++++++++++---------------------
 lib/librte_kni/rte_kni_fifo.h | 18 ++++++++++++++++
 lib/librte_mbuf/rte_mbuf.h    | 49 +++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 89 insertions(+), 24 deletions(-)

diff --git a/lib/librte_kni/rte_kni.c b/lib/librte_kni/rte_kni.c
index a80cefd..ad746ad 100644
--- a/lib/librte_kni/rte_kni.c
+++ b/lib/librte_kni/rte_kni.c
@@ -590,22 +590,21 @@ rte_kni_rx_burst(struct rte_kni *kni, struct rte_mbuf **mbufs, unsigned num)
 static void
 kni_free_mbufs(struct rte_kni *kni)
 {
-	int i, ret;
+	unsigned int freeing;
 	struct rte_mbuf *pkts[MAX_MBUF_BURST_NUM];
 
-	ret = kni_fifo_get(kni->free_q, (void **)pkts, MAX_MBUF_BURST_NUM);
-	if (likely(ret > 0)) {
-		for (i = 0; i < ret; i++)
-			rte_pktmbuf_free(pkts[i]);
+	freeing = kni_fifo_get(kni->free_q, (void **)pkts, MAX_MBUF_BURST_NUM);
+	if (likely(freeing > 0)) {
+		rte_pktmbuf_free_bulk(pkts, freeing);
 	}
 }
 
 static void
 kni_allocate_mbufs(struct rte_kni *kni)
 {
-	int i, ret;
-	struct rte_mbuf *pkts[MAX_MBUF_BURST_NUM];
-	void *phys[MAX_MBUF_BURST_NUM];
+	unsigned int count, put;
+	struct rte_mbuf *pkts[KNI_FIFO_COUNT_MAX];
+	void *phys[KNI_FIFO_COUNT_MAX];
 
 	RTE_BUILD_BUG_ON(offsetof(struct rte_mbuf, pool) !=
 			 offsetof(struct rte_kni_mbuf, pool));
@@ -628,28 +627,27 @@ kni_allocate_mbufs(struct rte_kni *kni)
 		return;
 	}
 
-	for (i = 0; i < MAX_MBUF_BURST_NUM; i++) {
-		pkts[i] = rte_pktmbuf_alloc(kni->pktmbuf_pool);
-		if (unlikely(pkts[i] == NULL)) {
-			/* Out of memory */
-			RTE_LOG(ERR, KNI, "Out of memory\n");
-			break;
-		}
-		phys[i] = va2pa(pkts[i]);
-	}
+	/* Calculate alloc queue free space */
+	count = kni_fifo_free_count(kni->alloc_q);
 
-	/* No pkt mbuf alocated */
-	if (i <= 0)
+	/* Get buffers from mempool */
+	if (rte_pktmbuf_alloc_bulk(kni->pktmbuf_pool, pkts, count) != 0) {
+		RTE_LOG(ERR, KNI, "Can`t allocate %d mbufs\n", count);
 		return;
+	}
 
-	ret = kni_fifo_put(kni->alloc_q, phys, i);
+	for (unsigned int i = 0; i < count; i++)
+		phys[i] = va2pa(pkts[i]);
 
-	/* Check if any mbufs not put into alloc_q, and then free them */
-	if (ret >= 0 && ret < i && ret < MAX_MBUF_BURST_NUM) {
-		int j;
+	/* Put buffers into alloc queue */
+	put = kni_fifo_put(kni->alloc_q, (void **)phys, count);
 
-		for (j = ret; j < i; j++)
+	/* Check if any mbufs not put into alloc_q, and then free them */
+	if (unlikely(put < count)) {
+		for (unsigned int j = put; j < count; j++) {
+			RTE_LOG(ERR, KNI, "Free allocated buffer\n");
 			rte_pktmbuf_free(pkts[j]);
+		}
 	}
 }
 
diff --git a/lib/librte_kni/rte_kni_fifo.h b/lib/librte_kni/rte_kni_fifo.h
index 8cb8587..361ddb0 100644
--- a/lib/librte_kni/rte_kni_fifo.h
+++ b/lib/librte_kni/rte_kni_fifo.h
@@ -91,3 +91,21 @@ kni_fifo_get(struct rte_kni_fifo *fifo, void **data, unsigned num)
 	fifo->read = new_read;
 	return i;
 }
+
+/**
+ * Get the num of elements in the fifo
+ */
+static inline unsigned
+kni_fifo_count(struct rte_kni_fifo *fifo)
+{
+	return (fifo->len + fifo->write - fifo->read) & (fifo->len - 1);
+}
+
+/**
+ * Get the num of available elements in the fifo
+ */
+static inline unsigned
+kni_fifo_free_count(struct rte_kni_fifo *fifo)
+{
+	return (fifo->read - fifo->write - 1) & (fifo->len - 1);
+}
diff --git a/lib/librte_mbuf/rte_mbuf.h b/lib/librte_mbuf/rte_mbuf.h
index 4476d75..69d314f 100644
--- a/lib/librte_mbuf/rte_mbuf.h
+++ b/lib/librte_mbuf/rte_mbuf.h
@@ -306,6 +306,9 @@ extern "C" {
 /** Alignment constraint of mbuf private area. */
 #define RTE_MBUF_PRIV_ALIGN 8
 
+/** Maximum number of mbufs freed in bulk. */
+#define RTE_MBUF_BULK_FREE 64
+
 /**
  * Get the name of a RX offload flag
  *
@@ -1261,6 +1264,52 @@ static inline void rte_pktmbuf_free(struct rte_mbuf *m)
 }
 
 /**
+ * Free n packets mbuf back into its original mempool.
+ *
+ * Free each mbuf, and all its segments in case of chained buffers. Each
+ * segment is added back into its original mempool.
+ *
+ * @param mp
+ *   The packets mempool.
+ * @param mbufs
+ *   The packets mbufs array to be freed.
+ * @param n
+ *   Number of packets.
+ */
+static inline void rte_pktmbuf_free_bulk(struct rte_mbuf **mbufs,
+		unsigned int n)
+{
+	void *tofree[RTE_MBUF_BULK_FREE];
+	struct rte_mempool *mp = NULL;
+	unsigned int i, count = 0;
+
+	for (i = 0; i < n; i++) {
+		struct rte_mbuf *m, *m_next;
+
+		for (m = mbufs[i]; m; m = m_next) {
+			m_next = m->next;
+
+			if (count > 0 &&
+			    (unlikely(m->pool != mp ||
+				    count == RTE_MBUF_BULK_FREE))) {
+				rte_mempool_put_bulk(mp, tofree, count);
+				count = 0;
+			}
+
+			mp = m->pool;
+
+			if (likely(__rte_pktmbuf_prefree_seg(m) != NULL)) {
+				m->next = NULL;
+				tofree[count++] = m;
+			}
+		}
+	}
+
+	if (likely(count > 0))
+		rte_mempool_put_bulk(mp, tofree, count);
+}
+
+/**
  * Creates a "clone" of the given packet mbuf.
  *
  * Walks through all segments of the given packet mbuf, and for each of them:
-- 
2.7.4