From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mo-p07-ob.rzone.de (mo-p07-ob.rzone.de [81.169.146.189]) by ozlabs.org (Postfix) with ESMTP id 0FFA0DDE01 for ; Tue, 13 Mar 2007 18:35:16 +1100 (EST) From: Stefan Roese To: linuxppc-dev@ozlabs.org Subject: Re: [PATCH] ppc: Add support for bigger page sizes than 4KB on PPC44x Date: Tue, 13 Mar 2007 08:37:05 +0100 References: <200703122254.27087.sr@denx.de> <1173769934.24454.67.camel@localhost.localdomain> In-Reply-To: <1173769934.24454.67.camel@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Message-Id: <200703130837.06339.sr@denx.de> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Tuesday 13 March 2007 08:12, Benjamin Herrenschmidt wrote: > While it's a good idea, there are a couple of issues with the patch: > > - It's arch/ppc. We shouldn't do new major features on this codebase. > You are welcome however in helping moving over 4xx to arch/powerpc :-) Yes, sure. But the project this patch was developed for started quite a while ago when absolutely no 4xx support was available in arch/powerpc. I'm of course aware that we have to move to arch/powerpc in the near future and am willing to help here. > - You only adapted head_4xx.S but the config option is global to all of > arch/ppc, thus changing it will probably break everything else. Make > sure the option is done in such a way that it can't be changed or the > kernel doesn't build if changed for a processor family where you haven't > implemented the support OK, will address this problem later. > - Have you tried other page sizes ? How hard would it be to support 16K > and what kind of performance numbers do you get with 16K ? It's a better > compromise for some applications as 64K causes significant bloat of the > page cache (among other things). No, we haven't tested other page sizes. We chose 64K because it is the stripe size of the RAID arrays. Thanks. Best regards, Stefan