if the mbuf has a valid flowid, use it instead of using siphash24

and a bunch of header fields we have to parse the mbuf for.

siphash24 is about 20% of the cost of sending a udp packet on a
trunk interface with tcpbench on my box. if there's a flowid set
we get all that back.

ok mpi@ mikeb@ sthen@

diff --git a/sys/net/if_trunk.c b/sys/net/if_trunk.c
index 8678fe4..4285dbe 100644 (file)
--- a/sys/net/if_trunk.c
+++ b/sys/net/if_trunk.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: if_trunk.c,v 1.119 2015/10/05 13:00:04 mikeb Exp $    */
+/*     $OpenBSD: if_trunk.c,v 1.120 2015/10/08 11:39:59 dlg Exp $      */
 
 /*
  * Copyright (c) 2005, 2006, 2007 Reyk Floeter <reyk@openbsd.org>
@@ -969,6 +969,9 @@ trunk_hashmbuf(struct mbuf *m, SIPHASH_KEY *key)
 #endif
        SIPHASH_CTX ctx;
 
+       if (m->m_pkthdr.flowid & M_FLOWID_VALID)
+               return (m->m_pkthdr.flowid & M_FLOWID_MASK);
+
        SipHash24_Init(&ctx, key);
        off = sizeof(*eh);
        if (m->m_len < off)