From mboxrd@z Thu Jan 1 00:00:00 1970 Received: with ECARTIS (v1.0.0; list linux-mips); Tue, 17 Sep 2002 21:38:33 +0200 (CEST) Received: from crack.them.org ([65.125.64.184]:28424 "EHLO crack.them.org") by linux-mips.org with ESMTP id ; Tue, 17 Sep 2002 21:38:33 +0200 Received: from nevyn.them.org ([66.93.61.169] ident=mail) by crack.them.org with asmtp (Exim 3.12 #1 (Debian)) id 17rP6y-0004Lw-00; Tue, 17 Sep 2002 15:38:20 -0500 Received: from drow by nevyn.them.org with local (Exim 3.35 #1 (Debian)) id 17rOAu-0007M8-00; Tue, 17 Sep 2002 15:38:20 -0400 Date: Tue, 17 Sep 2002 15:38:20 -0400 From: Daniel Jacobowitz To: Greg Lindahl Cc: Jun Sun , linux-mips@linux-mips.org Subject: Re: [RFC] FPU context switch Message-ID: <20020917193820.GA28255@nevyn.them.org> References: <20020917110423.E17321@mvista.com> <1032288140.28433.165.camel@gs256.sp.cs.cmu.edu> <20020917114831.G17321@mvista.com> <20020917120310.A2043@wumpus.internal.keyresearch.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20020917120310.A2043@wumpus.internal.keyresearch.com> User-Agent: Mutt/1.5.1i Return-Path: X-Envelope-To: <"|/home/ecartis/ecartis -s linux-mips"> (uid 0) X-Orcpt: rfc822;linux-mips@linux-mips.org Original-Recipient: rfc822;linux-mips@linux-mips.org X-archive-position: 213 X-ecartis-version: Ecartis v1.0.0 Sender: linux-mips-bounce@linux-mips.org Errors-to: linux-mips-bounce@linux-mips.org X-original-sender: dan@debian.org Precedence: bulk X-list: linux-mips On Tue, Sep 17, 2002 at 12:03:10PM -0700, Greg Lindahl wrote: > On Tue, Sep 17, 2002 at 11:48:31AM -0700, Jun Sun wrote: > > > I think this gives a big performance improvement because most processes > > don't use FPU during their runs but they all have used_math flag set! > > Jun, > > You really ought to prove that first. Many people spend a lot of time > optimizing things that aren't important. If it isn't important, than > the simplest scheme is the best choice. Oh, he's quite correct. There's a setjmp() early in the execution path, and it saves FP registers on machines with FP support configured on. So tasks are marked as FPU users. I've never thought of a terribly good way around this. -- Daniel Jacobowitz MontaVista Software Debian GNU/Linux Developer