Date: Sun, 30 Dec 2007 18:27:08 -0500 From: "Aryeh M. Friedman" <aryeh.friedman@gmail.com> To: =?UTF-8?B?RGFnLUVybGluZyBTbcO4cmdyYXY=?= <des@des.no> Cc: freebsd-hackers@freebsd.org, Ivan Voras <ivoras@freebsd.org> Subject: Re: BSD license compatible hash algorithm? Message-ID: <4778294C.3030905@gmail.com> In-Reply-To: <86r6h5zpr3.fsf@ds4.des.no> References: <5950EE0C-383D-4D6B-9991-A0DEABD2ADE4@u.washington.edu> <20071228003716.GB48997@lor.one-eyed-alien.net> <B8D4C3C6-B867-4550-9F17-4DC6930D10E2@u.washington.edu> <fl2qiv$qoh$1@ger.gmane.org> <4774EF27.90307@gmail.com> <86r6h5zpr3.fsf@ds4.des.no>
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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Dag-Erling Smørgrav wrote: > "Aryeh M. Friedman" <aryeh.friedman@gmail.com> writes: >> All hashs have issues with pooling.... see >> http://www.burtleburtle.net/bob/hash/index.html... btw it is a >> old wives tale that the number of buckets should be prime (mostly >> based on the very weak implementation Knuth offered) > > Not an "old wives' tale", but rather an easy way to implement a > hash algorithm that is good enough for most simple uses: metric > modulo table size, where metric is a number derived from the item > in such a manner as to give a good spread. Sorry for taking a while to reply.... but the above only applies if your using a very primitive hash like Knuth's multiplication one.... every modern hash I know of should have 2^k buckets actually for some k<2^32 [in almost all cases <2^16 except for algorithms like the one I mentioned I am working on which sets k=n where n=the bit count of the key]. - -- Aryeh M. Friedman FloSoft Systems http://www.flosoft-systems.com Developer, not business, friendly -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.4 (FreeBSD) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFHeClMzIOMjAek4JIRAlA+AKCVC0oOblPhF7QZARtkfUmdGX4hVACfcyPd qhtFfOt2lOaxcmCDt6/wXsE= =jztY -----END PGP SIGNATURE-----
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