packets: Do not initialize ct_orig_tuple.

Commit "odp: Support conntrack orig tuple key." introduced new fields
in struct 'pkt_metadata'.  pkt_metadata_init() is called for every
packet in the userspace datapath.  When testing a simple single
flow case with DPDK, we observe a lower throughput after the above
commit (it was 14.88 Mpps before, it is 13 Mpps after).

This patch skips initializing ct_orig_tuple in pkt_metadata_init().
It should be enough to initialize ct_state, because nobody should look
at ct_orig_tuple unless ct_state is != 0.

It's discussed at:
https://mail.openvswitch.org/pipermail/ovs-dev/2017-May/332419.html

Fixes: daf4d3c18da4("odp: Support conntrack orig tuple key.")
Signed-off-by: Daniele Di Proietto <diproiettod@vmware.com>
Signed-off-by: Bhanuprakash Bodireddy <bhanuprakash.bodireddy@intel.com>
Co-authored-by: Bhanuprakash Bodireddy <bhanuprakash.bodireddy@intel.com>
Signed-off-by: Darrell Ball <dlu998@gmail.com>
Signed-off-by: Ben Pfaff <blp@ovn.org>

diff --git a/lib/packets.h b/lib/packets.h
index a9d5e844eab8920a171b88e2cc1f28d07b3b4cd9..8c9c741fae74a6c08e1c00cde1cf6cc95eb9aef4 100644 (file)
--- a/lib/packets.h
+++ b/lib/packets.h
@@ -126,10 +126,18 @@ pkt_metadata_init_tnl(struct pkt_metadata *md)
 static inline void
 pkt_metadata_init(struct pkt_metadata *md, odp_port_t port)
 {
+    /* This is called for every packet in userspace datapath and affects
+     * performance if all the metadata is initialized. Hence, fields should
+     * only be zeroed out when necessary.
+     *
+     * Initialize only till ct_state. Once the ct_state is zeroed out rest
+     * of ct fields will not be looked at unless ct_state != 0.
+     */
+    memset(md, 0, offsetof(struct pkt_metadata, ct_orig_tuple_ipv6));
+
     /* It can be expensive to zero out all of the tunnel metadata. However,
      * we can just zero out ip_dst and the rest of the data will never be
      * looked at. */
-    memset(md, 0, offsetof(struct pkt_metadata, in_port));
     md->tunnel.ip_dst = 0;
     md->tunnel.ipv6_dst = in6addr_any;
     md->in_port.odp_port = port;