dpif-netdev: Eliminate two malloc() calls per packet sent to "userspace".

This is easy enough, so it seems worthwhile now that FreeBSD is starting
to make more use of the "userspace switch".

CC: Ed Maste <emaste@freebsd.org>
Signed-off-by: Ben Pfaff <blp@nicira.com>

diff --git a/lib/dpif-netdev.c b/lib/dpif-netdev.c
index 3d01b17aabc0c8ec97f884dd0453b747568632c9..144b6b63375c91f5ff937fd013d62849f6001dd4 100644 (file)
--- a/lib/dpif-netdev.c
+++ b/lib/dpif-netdev.c
@@ -70,8 +70,13 @@ enum { MAX_QUEUE_LEN = 128 };   /* Maximum number of packets per queue. */
 enum { QUEUE_MASK = MAX_QUEUE_LEN - 1 };
 BUILD_ASSERT_DECL(IS_POW2(MAX_QUEUE_LEN));
 
+struct dp_netdev_upcall {
+    struct dpif_upcall upcall;  /* Queued upcall information. */
+    struct ofpbuf buf;          /* ofpbuf instance for upcall.packet. */
+};
+
 struct dp_netdev_queue {
-    struct dpif_upcall *upcalls[MAX_QUEUE_LEN];
+    struct dp_netdev_upcall upcalls[MAX_QUEUE_LEN];
     unsigned int head, tail;
 };
 
@@ -259,10 +264,8 @@ dp_netdev_purge_queues(struct dp_netdev *dp)
         struct dp_netdev_queue *q = &dp->queues[i];
 
         while (q->tail != q->head) {
-            struct dpif_upcall *upcall = q->upcalls[q->tail++ & QUEUE_MASK];
-
-            ofpbuf_delete(upcall->packet);
-            free(upcall);
+            struct dp_netdev_upcall *u = &q->upcalls[q->tail++ & QUEUE_MASK];
+            ofpbuf_uninit(&u->buf);
         }
     }
 }
@@ -960,13 +963,13 @@ dpif_netdev_recv(struct dpif *dpif, struct dpif_upcall *upcall,
 {
     struct dp_netdev_queue *q = find_nonempty_queue(dpif);
     if (q) {
-        struct dpif_upcall *u = q->upcalls[q->tail++ & QUEUE_MASK];
-        *upcall = *u;
-        free(u);
+        struct dp_netdev_upcall *u = &q->upcalls[q->tail++ & QUEUE_MASK];
+
+        *upcall = u->upcall;
+        upcall->packet = buf;
 
         ofpbuf_uninit(buf);
-        *buf = *upcall->packet;
-        free(upcall->packet);
+        *buf = u->buf;
 
         return 0;
     } else {
@@ -1088,6 +1091,7 @@ dp_netdev_output_userspace(struct dp_netdev *dp, const struct ofpbuf *packet,
                          int queue_no, const struct flow *flow, uint64_t arg)
 {
     struct dp_netdev_queue *q = &dp->queues[queue_no];
+    struct dp_netdev_upcall *u;
     struct dpif_upcall *upcall;
     struct ofpbuf *buf;
     size_t key_len;
@@ -1097,22 +1101,23 @@ dp_netdev_output_userspace(struct dp_netdev *dp, const struct ofpbuf *packet,
         return ENOBUFS;
     }
 
-    buf = ofpbuf_new(ODPUTIL_FLOW_KEY_BYTES + 2 + packet->size);
+    u = &q->upcalls[q->head++ & QUEUE_MASK];
+
+    buf = &u->buf;
+    ofpbuf_init(buf, ODPUTIL_FLOW_KEY_BYTES + 2 + packet->size);
     odp_flow_key_from_flow(buf, flow);
     key_len = buf->size;
     ofpbuf_pull(buf, key_len);
     ofpbuf_reserve(buf, 2);
     ofpbuf_put(buf, packet->data, packet->size);
 
-    upcall = xzalloc(sizeof *upcall);
+    upcall = &u->upcall;
     upcall->type = queue_no;
     upcall->packet = buf;
     upcall->key = buf->base;
     upcall->key_len = key_len;
     upcall->userdata = arg;
 
-    q->upcalls[q->head++ & QUEUE_MASK] = upcall;
-
     return 0;
 }