Date: Thu, 20 Jan 2011 16:52:15 +0100 From: Alexander Leidinger <Alexander@Leidinger.net> To: Gleb Kurtsou <gleb.kurtsou@gmail.com> Cc: freebsd-hackers@freebsd.org Subject: Re: [rfc] Replacing FNV and hash32 with Paul Hsieh's SuperFastHash Message-ID: <20110120165215.1794698qw7ejr18g@webmail.leidinger.net> In-Reply-To: <20101223224619.GA21984@tops> References: <20101223224619.GA21984@tops>
next in thread | previous in thread | raw e-mail | index | archive | help
Quoting Gleb Kurtsou <gleb.kurtsou@gmail.com> (from Fri, 24 Dec 2010 00:46:20 +0200): > Hi, > > I've recently noticed that hash table use in nullfs was inefficient, 1/3 > to half of buckets remained unused. I've started investigating it > further and came across SuperFastHash hashing function, SFH > (SuperFastHash) has BSD license, used in WebKit and other open source > projects. Detailed description and Comparision with FNV and Bob Jenkin's > hash can be found here: > http://www.azillionmonkeys.com/qed/hash.html I found some web pages which tell about an unfair speed comparision and about a collision problem in SFH: http://coding.derkeiler.com/Archive/General/comp.programming/2005-03/0650.html http://www.team5150.com/~andrew/blog/2007/03/breaking_superfasthash.html http://blog.clawpaws.net/post/2007/04/22/Good-Hash-Functions It may be that this is not an issue for the use case we have here, but blindly replacing it without looking at the above web pages looks a little bit risky to me. Bye, Alexander. -- The use of money is all the advantage there is to having money. -- Benjamin Franklin http://www.Leidinger.net Alexander @ Leidinger.net: PGP ID = B0063FE7 http://www.FreeBSD.org netchild @ FreeBSD.org : PGP ID = 72077137
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20110120165215.1794698qw7ejr18g>