Date: 14 May 1999 16:29:32 +0200 From: Dag-Erling Smorgrav <des@flood.ping.uio.no> To: Eivind Eklund <eivind@FreeBSD.ORG> Cc: Alfred Perlstein <bright@rush.net>, Brett Glass <brett@lariat.org>, Jamie Bowden <ragnar@sysabend.org>, chat@FreeBSD.ORG Subject: Re: BSD, GPL, the world today. (fwd) Message-ID: <xzpr9oj3esz.fsf@localhost.ping.uio.no> In-Reply-To: Eivind Eklund's message of "Fri, 14 May 1999 16:05:46 %2B0200" References: <4.2.0.37.19990513114425.04421810@localhost> <Pine.BSF.3.96.990513141917.26546V-100000@cygnus.rush.net> <19990514160546.A23300@bitbox.follo.net>
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[I consider myself a friend of Alfred's as well, which I guess entitles me to pick on him ;P] Eivind Eklund <eivind@FreeBSD.ORG> writes: > To state this another way: Alfred, you're repeating a lot of myths. > If you're going to have an opinion about this stuff (and you don't > have to - saying "I don't know enough to have an opinion" is fair > statement), you need to get the facts. Compiler theory, memory > management speed measurements, cache handling, average number of bugs > connected to different programming paradigms, etc. To pick one item in the above list which is becoming increasingly important, C is too low-level to allow the compiler to properly optimize for efficient cache use, and lacks constructs which would allow the programmer to help the compiler do this. The reason why I'm saying it's becoming increasingly important is that memory (and cache) speed is lagging way behind CPU speed, and the gap is widening every day. Consider an n-way superscalar CPU with, say, five issues per clock, running at one gigahertz (totalling five gigaissues per second in the best case), and a memory hierarchy with a level 1 cache running at CPU speed and a primary store with a 100 ns average acess, a cache miss costs 500 instructions. Given those premises, you really, really want to avoid cache misses as much as possible. DES -- Dag-Erling Smorgrav - des@flood.ping.uio.no To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-chat" in the body of the message
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