From mboxrd@z Thu Jan 1 00:00:00 1970 Received: with ECARTIS (v1.0.0; list linux-mips); Mon, 17 Nov 2003 22:53:49 +0000 (GMT) Received: from p508B6BAF.dip.t-dialin.net ([IPv6:::ffff:80.139.107.175]:9960 "EHLO mail.linux-mips.net") by linux-mips.org with ESMTP id ; Mon, 17 Nov 2003 22:53:37 +0000 Received: from dea.linux-mips.net (localhost [127.0.0.1]) by mail.linux-mips.net (8.12.8/8.12.8) with ESMTP id hAHMqvA0016385; Mon, 17 Nov 2003 23:52:57 +0100 Received: (from ralf@localhost) by dea.linux-mips.net (8.12.8/8.12.8/Submit) id hAHMqmX3016381; Mon, 17 Nov 2003 23:52:48 +0100 Date: Mon, 17 Nov 2003 23:52:48 +0100 From: Ralf Baechle To: Jeffrey Baitis Cc: linux-mips@linux-mips.org, Adam_Kiepul@pmc-sierra.com, "Mr. Brian R. Gunnison" , Francis Yu , Johnny Lam Subject: Re: Newbie R5K questions -- -mips2 vs -mips4; is n32 ABI supported by Linux? Message-ID: <20031117225248.GA15868@linux-mips.org> References: <1069106666.1829.323.camel@powerpuff.evo1.pas.lab> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1069106666.1829.323.camel@powerpuff.evo1.pas.lab> User-Agent: Mutt/1.4.1i 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: 3636 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: ralf@linux-mips.org Precedence: bulk X-list: linux-mips On Mon, Nov 17, 2003 at 02:04:26PM -0800, Jeffrey Baitis wrote: > I'm currently trying to increase performance on our PMC-Sierra RM5231 > system by taking advantage of the MIPS IV ISA. This processor has a > 32-bit address bus interface with 64-bit GPRs, so I guess that the > choice of -mabi=n32 is ideal for this processor. In addition to what Daniel just said ... N32 requires a 64-bit kernel to run on which is significantly larger thereby causing more cache misses so a 64-bit kernel is often slower. On the kernel side a 64-bit kernel is drastically better at handling large amounts of memory, so once a 32-bit kernel needs highmem the 64-bit kernel will win the race. Often these effects influence performance more than what you might gain from exploiting a new ISA. Ralf