Date: Fri, 06 Sep 2002 19:24:53 -0700 From: Peter Wemm <peter@wemm.org> To: Kenneth Culver <culverk@yumyumyum.org> Cc: Kris Kennaway <kris@obsecurity.org>, Maxime Henrion <mux@FreeBSD.ORG>, cvs-committers@FreeBSD.ORG, cvs-all@FreeBSD.ORG, current@FreeBSD.ORG Subject: Re: HEADS UP: SSE instructions (Re: cvs commit: src/share/mk bsd.cpu.mk) Message-ID: <20020907022453.DD7F82A7D6@canning.wemm.org> In-Reply-To: <20020906214850.J46717-100000@alpha.yumyumyum.org>
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Kenneth Culver wrote: > > I assume the compiler is not stupid enough to try and use both when that > > is impossible. Don't forget this is all just passing a CPU name to gcc > > which actually decides what instructions to use. > > That's not what I mean... What I mean is that if one application is using > SSE, and the other wants to use 3dnow, this will incur a performance > penalty (although I'm not sure how much or how noticable it is), so some > people may not want to have SSE enabled. If you set your CPUTYPE cause gcc to *generate* sse instructions, then it will crash the binary if the kernel doesn't support it. As far as I understood it, the 'dont mix 3dnow and SSE' thing was exactly that.. do not mix the instructions together in the same application stream.. Apparently the instruction decoder wasn't tuned for both in the same data stream. Cheers, -Peter -- Peter Wemm - peter@wemm.org; peter@FreeBSD.org; peter@yahoo-inc.com "All of this is for nothing if we don't go to the stars" - JMS/B5 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe cvs-all" in the body of the message
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