From owner-freebsd-hackers Thu Jan 14 21:59:24 1999 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id VAA24183 for freebsd-hackers-outgoing; Thu, 14 Jan 1999 21:59:24 -0800 (PST) (envelope-from owner-freebsd-hackers@FreeBSD.ORG) Received: from obie.softweyr.com ([204.68.178.33]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id VAA24176 for ; Thu, 14 Jan 1999 21:59:21 -0800 (PST) (envelope-from wes@softweyr.com) Received: from softweyr.com (zaphod.softweyr.com [204.68.178.35]) by obie.softweyr.com (8.8.8/8.8.8) with ESMTP id WAA09037; Thu, 14 Jan 1999 22:56:26 -0700 (MST) (envelope-from wes@softweyr.com) Message-ID: <369ED88A.873515B3@softweyr.com> Date: Thu, 14 Jan 1999 22:56:26 -0700 From: Wes Peters Organization: Softweyr llc X-Mailer: Mozilla 4.5 [en] (X11; U; FreeBSD 3.0-RELEASE i386) X-Accept-Language: en MIME-Version: 1.0 To: Jason Thorpe CC: Matthew Dillon , "Robert V. Baron" , "Ron G. Minnich" , zhihuizhang , hackers Subject: Re: TSS and context switch References: <199901150436.UAA08145@lestat.nas.nasa.gov> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG Jason Thorpe wrote: > > 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 :-) ALL of the instructions on the VAX were like this, and some sucked even worse. ;^) Intel's history in this area dates all the way back to the 286 and PUSHA instruction, which was generally much slower than just pushing the registers you were going to diddle. Too bad they never grokked the concept of movem, huh? -- "Where am I, and what am I doing in this handbasket?" Wes Peters Softweyr LLC http://www.softweyr.com/~softweyr wes@softweyr.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message