[dpdk-dev] [PATCH v4 1/1] mbuf: add bulk free function

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

Add function for freeing a bulk of mbufs.

v4:
* Marked as experimental by adding __rte_experimental.
* Add function to experimental section of map file.
* Fix source code formatting regarding pointer to pointer.
* Squashed multiple modifications into one.
v3:
* Bugfix: Handle pakets with multiple segments.
* Added inline helper function, mainly for readability.
* Fix source code formatting regarding indentation.
v2:
* Function is not inline.
* Optimized to free multible mbufs belonging to the same mempool in
bulk. Inspired by ixgbe_tx_free_bufs(), but allowing NULL pointers
in the array, just like rte_pktmbuf_free() can take a NULL pointer.
* Use unsigned int instead of unsigned. Passes checkpatch, but
mismatches the original coding style of the modified files.
* Fixed a typo in the description headline: mempools is plural.

Signed-off-by: Morten Brørup <mb@smartsharesystems.com>
---
 lib/librte_mbuf/rte_mbuf.c           | 50 ++++++++++++++++++++++++++++
 lib/librte_mbuf/rte_mbuf.h           | 12 +++++++
 lib/librte_mbuf/rte_mbuf_version.map |  1 +
 3 files changed, 63 insertions(+)

diff --git a/lib/librte_mbuf/rte_mbuf.c b/lib/librte_mbuf/rte_mbuf.c
index 37718d49c..0088117a3 100644
--- a/lib/librte_mbuf/rte_mbuf.c
+++ b/lib/librte_mbuf/rte_mbuf.c
@@ -245,6 +245,56 @@ int rte_mbuf_check(const struct rte_mbuf *m, int is_header,
 	return 0;
 }
 
+/**
+ * Size of the array holding mbufs from the same membool to be freed in bulk.
+ */
+#define RTE_PKTMBUF_FREE_BULK_SZ 64
+
+/**
+ * @internal helper function for freeing a bulk of mbufs via an array holding
+ * mbufs from the same mempool.
+ */
+static __rte_always_inline void
+rte_pktmbuf_free_seg_via_array(struct rte_mbuf *m,
+	struct rte_mbuf ** const free, unsigned int * const nb_free)
+{
+	m = rte_pktmbuf_prefree_seg(m);
+	if (likely(m != NULL)) {
+		if (*nb_free >= RTE_PKTMBUF_FREE_BULK_SZ ||
+		    (*nb_free > 0 && m->pool != free[0]->pool)) {
+			rte_mempool_put_bulk(free[0]->pool, (void **)free,
+					     *nb_free);
+			*nb_free = 0;
+		}
+
+		free[(*nb_free)++] = m;
+	}
+}
+
+/* Free a bulk of mbufs back into their original mempools. */
+void rte_pktmbuf_free_bulk(struct rte_mbuf **mbufs, unsigned int count)
+{
+	struct rte_mbuf *m, *m_next, *free[RTE_PKTMBUF_FREE_BULK_SZ];
+	unsigned int idx, nb_free = 0;
+
+	for (idx = 0; idx < count; idx++) {
+		m = mbufs[idx];
+		if (unlikely(m == NULL))
+			continue;
+
+		__rte_mbuf_sanity_check(m, 1);
+
+		do {
+			m_next = m->next;
+			rte_pktmbuf_free_seg_via_array(m, free, &nb_free);
+			m = m_next;
+		} while (m != NULL);
+	}
+
+	if (nb_free > 0)
+		rte_mempool_put_bulk(free[0]->pool, (void **)free, nb_free);
+}
+
 /* dump a mbuf on console */
 void
 rte_pktmbuf_dump(FILE *f, const struct rte_mbuf *m, unsigned dump_len)
diff --git a/lib/librte_mbuf/rte_mbuf.h b/lib/librte_mbuf/rte_mbuf.h
index 98225ec80..871145796 100644
--- a/lib/librte_mbuf/rte_mbuf.h
+++ b/lib/librte_mbuf/rte_mbuf.h
@@ -1907,6 +1907,18 @@ static inline void rte_pktmbuf_free(struct rte_mbuf *m)
 	}
 }
 
+/**
+ * Free a bulk of mbufs back into their original mempools.
+ *
+ *  @param mbufs
+ *    Array of pointers to mbufs.
+ *    The array may contain NULL pointers.
+ *  @param count
+ *    Array size.
+ */
+__rte_experimental
+void rte_pktmbuf_free_bulk(struct rte_mbuf **mbufs, unsigned int count);
+
 /**
  * Creates a "clone" of the given packet mbuf.
  *
diff --git a/lib/librte_mbuf/rte_mbuf_version.map b/lib/librte_mbuf/rte_mbuf_version.map
index 2662a37bf..cd6154ef2 100644
--- a/lib/librte_mbuf/rte_mbuf_version.map
+++ b/lib/librte_mbuf/rte_mbuf_version.map
@@ -50,4 +50,5 @@ EXPERIMENTAL {
 	global:
 
 	rte_mbuf_check;
+	rte_pktmbuf_free_bulk;
 } DPDK_18.08;
-- 
2.17.1