Date: Thu, 14 Jan 1999 20:36:27 -0800 From: Jason Thorpe <thorpej@nas.nasa.gov> To: Matthew Dillon <dillon@apollo.backplane.com> Cc: "Robert V. Baron" <rvb@cs.cmu.edu>, "Ron G. Minnich" <rminnich@Sarnoff.COM>, zhihuizhang <bf20761@binghamton.edu>, hackers <freebsd-hackers@FreeBSD.ORG> Subject: Re: TSS and context switch Message-ID: <199901150436.UAA08145@lestat.nas.nasa.gov>
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On Thu, 14 Jan 1999 20:08:32 -0800 (PST) Matthew Dillon <dillon@apollo.backplane.com> wrote: > There are a number of intel instructions which were designed to > run fast on a 486, which turn out to be dogs on higher-end cpu's. > For example, the ENTER instruction is considerably slower then > doing the frame pointer / stack pointer manipulation manually. > > There are many others. I distinctly remember there being several instructions on the VAX that were like this (perhaps the polynomial evaluation instructions.. it's been a while :-) ... you were better off open-coding them than using the single instruction :-) Jason R. Thorpe thorpej@nas.nasa.gov NASA Ames Research Center Home: +1 408 866 1912 NAS: M/S 258-5 Work: +1 650 604 0935 Moffett Field, CA 94035 Pager: +1 650 940 5942 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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