Date: Thu, 10 Jan 2002 14:57:53 -0800 From: Terry Lambert <tlambert2@mindspring.com> To: Nate Williams <nate@yogotech.com> Cc: Kelly Yancey <kbyanc@posi.net>, Alfred Perlstein <bright@mu.org>, Daniel Eischen <eischen@pcnet1.pcnet.com>, Dan Eischen <eischen@vigrid.com>, Peter Wemm <peter@wemm.org>, Archie Cobbs <archie@dellroad.org>, arch@FreeBSD.ORG Subject: Re: Request for review: getcontext, setcontext, etc Message-ID: <3C3E1C71.415334E2@mindspring.com> References: <Pine.BSF.4.21.0201101401420.6961-100000@gateway.posi.net> <3C3E1870.1E0DA81F@mindspring.com> <15422.6499.274704.270810@caddis.yogotech.com>
next in thread | previous in thread | raw e-mail | index | archive | help
Nate Williams wrote: > > Remember that this is only true if someone is stupid enough to > > use the FPU, which is only useful for very specific tasks, most > > of which are non-threaded. > > Huh? Methinks Terry needs to make assume the world is just a *teeny* > bit larger than his narrow-view. There are several real reasons for threading, and a lot of bogus ones. The primary reason given these days is SMP scalability, even though I don't see anyone carrying this to its logical conclusion by interleaving seperate thread instructions to the Pentium 4 processors, which reall do perform better than the Pentium 3's, but only if you do that. Most people use threads as a crutch, because they are incapable of building a proper finite state automaton, or to let people who can only think linearly still contribute usefully to a project's code base. I personally have done a lot of FPU-requiring code, over my own checkered past (8-)), but I have to say that the vast majority of the code out there isn't FPU-requiring. > Even simple statistics use FP math. You're implying that FPU should > only be used by folks who have a real *NEED* for it, which is humerous > considering you're the one who usually bangs on the drum to make FreeBSD > useful for more folks. :) I think I lost that battle when it was decided that FreeBSD straight off a CDROM distribution will no longer run on the 386, which was an inevitability as soon as we started needing to "harvet entropy" just to boot. I'm not saying that the FPU shouldn't be used by people who have need of it (e.g. people unable to download integer SIN and COS tables, for example... 8-)), but I *am* saying that if there is no way around a kernel entry for a threads context switch because of the frigging FPU context, then only the programs actually using the FPU should pay that penalty. Realize that I believe that most programs, going forward, will *not* be threaded, if their programmers know what they are doing, sinc ethere are usually better ways of solving any probably that can be solved that way, save SMP scalability (and I'm not entirely convinced there, either, based on the common locality of reference arguments, that they wouldn't be better off running two seperate instances, rather than one instance with two threads). -- Terry To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?3C3E1C71.415334E2>