Change the PF hash from Jenkins to Murmur3. In forwarding tests

this showed a conservative 3% incrase in PPS.

Differential Revision:	https://reviews.freebsd.org/D461
Submitted by:	des
Reviewed by:	emaste
MFC after:	1 month

1 files changed, 74 insertions, 0 deletions

diff --git a/sys/libkern/murmur3_32.c b/sys/libkern/murmur3_32.c
new file mode 100644
index 0000000..05ce2c5
--- /dev/null
+++ b/sys/libkern/murmur3_32.c
@@ -0,0 +1,74 @@
+/*-
+ * 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)))
+
+/*
+ * $FreeBSD$
+ * 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);
+}
+