From owner-freebsd-hackers Thu Jan 14 20:40:03 1999 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id UAA14156 for freebsd-hackers-outgoing; Thu, 14 Jan 1999 20:40:03 -0800 (PST) (envelope-from owner-freebsd-hackers@FreeBSD.ORG) Received: from lestat.nas.nasa.gov (lestat.nas.nasa.gov [129.99.50.29]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id UAA14075 for ; Thu, 14 Jan 1999 20:39:59 -0800 (PST) (envelope-from thorpej@lestat.nas.nasa.gov) Received: from lestat (localhost [127.0.0.1]) by lestat.nas.nasa.gov (8.8.8/8.6.12) with ESMTP id UAA08145; Thu, 14 Jan 1999 20:36:27 -0800 (PST) Message-Id: <199901150436.UAA08145@lestat.nas.nasa.gov> To: Matthew Dillon Cc: "Robert V. Baron" , "Ron G. Minnich" , zhihuizhang , hackers Subject: Re: TSS and context switch Reply-To: Jason Thorpe From: Jason Thorpe Date: Thu, 14 Jan 1999 20:36:27 -0800 Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On Thu, 14 Jan 1999 20:08:32 -0800 (PST) Matthew Dillon 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