Date: Mon, 29 Jan 2001 22:07:46 +0100 From: Poul-Henning Kamp <phk@critter.freebsd.dk> To: Bakul Shah <bakul@bitblocks.com> Cc: Matt Dillon <dillon@earth.backplane.com>, hackers@FreeBSD.ORG Subject: Re: [kernel patch] fcntl(...) to close many descriptors Message-ID: <24289.980802466@critter> In-Reply-To: Your message of "Mon, 29 Jan 2001 12:59:53 PST." <3A75D9C9.1C59ACBA@bitblocks.com>
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In message <3A75D9C9.1C59ACBA@bitblocks.com>, Bakul Shah writes: >This caught my eye: > >> Besides, there is no such thing as a >> perfect hash ... at least not one that has a small enough index range >> to be useful in a table lookup. > >If you can get to old CACMs see `Minimal Perfect Hash Functions Made Simple' >by Richard J. Cichelli, Comm. of ACM, Jan 1980. AFAIK gperf uses some >variation of that algorithm and may have some details. A minimal perfect hash >function is only worth it (IMHO) when the set of input keys is mostly fixed and >the hash function is used many many times (e.g. programming language keywords). And even then it's seldom worth it according to the people behind the LCC compiler... -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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