3 ms·

Comparing xxHash with FNV is a strawman, it's apples and oranges in terms of quality. You are discounting xxHash considerably. xxHash is one of the best, if no

Comparing xxHash with FNV is a strawman, it's apples and oranges in terms of quality. You are discounting xxHash considerably. xxHash is one of the best, if not the best, all factors considered. SMHasher: xxHash, speed=5.4 GB/s, quality=10 MurmurHash 3a, speed=2.7 GB/s, quality=10 SBox, speed=1.4 GB/s, quality=9 Lookup3, speed=1.2 GB/s, quality=9 CityHash64, speed=1.05 GB/s, quality=10 FNV, speed=0.55 GB/s, quality=5 CRC32, speed=0.43 GB/s, quality=9 MD5-32, speed=0.33 GB/s, quality=10 SHA1-32, speed=0.28 GB/s, quality=10

jandrewrogers 11y ago
With all due respect, xxHash is a decent hash function but you are comparing it against some relatively weak or slow hash functions. As was pointed out last time this came up, the Metro64 hash example I offered is simultaneously faster and higher quality than xxHash. There are hash functions that are faster than xxHash and stronger than some of the cryptographic hashes, and xxHash definitely has much more bias than even MD5. Getting a perfect score with SMHasher is table stakes. The default settings on SMHasher are much too loose for current research; I know it well, I have hacked it extensively. A state-of-the-art non-cryptographic hash function today generally has the following properties: - statistical quality greater than or equal to MD5, a cryptographic hash. xxHash is not close to MD5 in quality. - faster than xxHash on large keys, and for really good hashes, memory bandwidth bound. (Metro64 is, again, faster than xxHash, though not memory bandwidth bound.) - faster than xxHash on small keys (Metro64, to use that example, is almost 2x faster) There are a lot of good hash functions being developed by researchers. But empirically, xxHash is nowhere near the state-of-the-art any way you slice it. It is a decent hash function but there are many functions produced by many researchers that are both faster and higher quality. It isn't personal, people can measure it for themselves.
- jorangreef 11y ago
  Yes, I remember reading your post on Metro64 at the time: http://www.jandrewrogers.com/2015/05/27/metrohash/ http://www.jandrewrogers.com/2015/05/27/metrohash/ Interesting that you based your results there on SMHasher. Are there better benchmarks available?

jandrewrogers 11y ago

With all due respect, xxHash is a decent hash function but you are comparing it against some relatively weak or slow hash functions. As was pointed out last time this came up, the Metro64 hash example I offered is simultaneously faster and higher quality than xxHash. There are hash functions that are faster than xxHash and stronger than some of the cryptographic hashes, and xxHash definitely has much more bias than even MD5. Getting a perfect score with SMHasher is table stakes. The default settings on SMHasher are much too loose for current research; I know it well, I have hacked it extensively. A state-of-the-art non-cryptographic hash function today generally has the following properties: - statistical quality greater than or equal to MD5, a cryptographic hash. xxHash is not close to MD5 in quality. - faster than xxHash on large keys, and for really good hashes, memory bandwidth bound. (Metro64 is, again, faster than xxHash, though not memory bandwidth bound.) - faster than xxHash on small keys (Metro64, to use that example, is almost 2x faster) There are a lot of good hash functions being developed by researchers. But empirically, xxHash is nowhere near the state-of-the-art any way you slice it. It is a decent hash function but there are many functions produced by many researchers that are both faster and higher quality. It isn't personal, people can measure it for themselves.

jorangreef 11y ago
Yes, I remember reading your post on Metro64 at the time: http://www.jandrewrogers.com/2015/05/27/metrohash/ http://www.jandrewrogers.com/2015/05/27/metrohash/ Interesting that you based your results there on SMHasher. Are there better benchmarks available?