Index: sys/conf/files
===================================================================
--- sys/conf/files
+++ sys/conf/files
@@ -3175,6 +3175,7 @@
 libkern/inet_ntop.c		standard
 libkern/inet_pton.c		standard
 libkern/jenkins_hash.c		standard
+libkern/murmur3_32.c		standard
 libkern/mcount.c		optional profiling-routine
 libkern/memcchr.c		standard
 libkern/memchr.c		optional fdt | gdb
Index: sys/libkern/murmur3_32.c
===================================================================
--- /dev/null
+++ sys/libkern/murmur3_32.c
@@ -0,0 +1,73 @@
+/*-
+ * Copyright (c) 2014 Dag-Erling Smørgrav
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/hash.h>
+#include <sys/endian.h>
+#include <sys/stdint.h>
+#include <sys/types.h>
+
+#define rol32(i32, n) ((i32) << (n) | (i32) >> (32 - (n)))
+
+/*
+ * Simple implementation of the Murmur3-32 hash function optimized for
+ * aligned sequences of 32-bit words.  If len is not a multiple of 4, it
+ * will be rounded down, droping trailer bytes.
+ */
+uint32_t
+murmur3_aligned_32(const void *data, size_t len, uint32_t seed)
+{
+	const uint32_t *data32;
+	uint32_t hash, k;
+	size_t res;
+
+	/* initialize */
+	len -= len % sizeof(*data32);
+	res = len;
+	data32 = data;
+	hash = seed;
+
+	/* iterate */
+	for (res = 0; res < len; res += sizeof(*data32), data32++) {
+		k = le32toh(*data32);
+		k *= 0xcc9e2d51;
+		k = rol32(k, 15);
+		k *= 0x1b873593;
+		hash ^= k;
+		hash = rol32(hash, 13);
+		hash *= 5;
+		hash += 0xe6546b64;
+	}
+
+	/* finalize */
+	hash ^= (uint32_t)len;
+	hash ^= hash >> 16;
+	hash *= 0x85ebca6b;
+	hash ^= hash >> 13;
+	hash *= 0xc2b2ae35;
+	hash ^= hash >> 16;
+	return (hash);
+}
+
Index: sys/netpfil/pf/pf.c
===================================================================
--- sys/netpfil/pf/pf.c
+++ sys/netpfil/pf/pf.c
@@ -374,9 +374,9 @@
 {
 	uint32_t h;
 
-	h = jenkins_hash32((uint32_t *)sk,
-	    sizeof(struct pf_state_key_cmp)/sizeof(uint32_t),
-	    V_pf_hashseed);
+	h = murmur3_aligned_32((uint32_t *)sk,
+			       sizeof(struct pf_state_key_cmp),
+			       V_pf_hashseed);
 
 	return (h & pf_hashmask);
 }
@@ -388,12 +388,12 @@
 
 	switch (af) {
 	case AF_INET:
-		h = jenkins_hash32((uint32_t *)&addr->v4,
-		    sizeof(addr->v4)/sizeof(uint32_t), V_pf_hashseed);
+		h = murmur3_aligned_32((uint32_t *)&addr->v4,
+				       sizeof(addr->v4), V_pf_hashseed);
 		break;
 	case AF_INET6:
-		h = jenkins_hash32((uint32_t *)&addr->v6,
-		    sizeof(addr->v6)/sizeof(uint32_t), V_pf_hashseed);
+		h = murmur3_aligned_32((uint32_t *)&addr->v6,
+				       sizeof(addr->v6), V_pf_hashseed);
 		break;
 	default:
 		panic("%s: unknown address family %u", __func__, af);
Index: sys/sys/hash.h
===================================================================
--- sys/sys/hash.h
+++ sys/sys/hash.h
@@ -125,6 +125,9 @@
  */
 uint32_t jenkins_hash(const void *, size_t, uint32_t);
 uint32_t jenkins_hash32(const uint32_t *, size_t, uint32_t);
+
+uint32_t murmur3_aligned_32(const void *data, size_t len, uint32_t seed);
+
 #endif /* _KERNEL */
 
 #endif /* !_SYS_HASH_H_ */