Date: Tue, 21 Dec 1999 08:35:50 +0100 (CET) From: Oliver Fromme <olli@dorifer.heim3.tu-clausthal.de> To: freebsd-stable@FreeBSD.ORG Subject: Re: AMD 3DNow instructions on FreeBSD Message-ID: <199912210735.IAA26624@dorifer.heim3.tu-clausthal.de>
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Wilko Bulte wrote in list.freebsd-stable: > On Mon, Dec 20, 1999 at 07:36:31PM +0100, Oliver Fromme wrote: > [...] > > About 50%, that is, about 4.5 hours (instead of 9) on average > > per work unit, on an Athlon-500. And I did only optimize the > > FFT and didn't touch the rest. With a bit more effort, further > > improvements would be certainly possible. > > Wow! Quite a difference. Not having an Athlon but > > CPU: AMD-K6(tm) 3D processor (399.81-MHz 586-class CPU) > Origin = "AuthenticAMD" Id = 0x58c Stepping = 12 > AMD Features=0x80000800<SYSCALL,3DNow!> > > would that also make such a difference on the K6-2? Athlon has > different 3Dnow I think ?? The difference would be somewhat smaller, but there would certainly be a difference, too. The Athlon supports the same 3DNow instruction as the K6 family, but it also supports some additional instructions which are very useful. If you're interested in the details, I recommend the following documents: "AMD Athlon Processor x86 Code Optimization Guide" (22007) "3DNow Technology Manual" (21928) "MMX Enhanced Processor Multimedia Technology" (20726) "AMD Extensions to the 3DNow and MMX Instruction Sets" (22466) The number in parentheses is the AMD document order number. All of these documents can be order from AMD on CD-ROM. They can also be downloaded from AMD's web site at the following URL in PDF format: http://www.amd.com/support/techdocdir.html 3DNow instructions work on floating point values, while MMX instructions work on integer values. However, 3DNow code uses the same registers as MMX instructions, so it is common to intermix them (for example, use MMX instructions to move values into registers, then use 3DNow instructions for computation, then use an MMX instruction to negate the result). Regards Oliver -- Oliver Fromme, Leibnizstr. 18/61, 38678 Clausthal, Germany (Info: finger userinfo:olli@dorifer.heim3.tu-clausthal.de) "In jedem Stück Kohle wartet ein Diamant auf seine Geburt" (Terry Pratchett) To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message
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