From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTP id 80A91DDDEF for ; Wed, 14 Mar 2007 00:54:35 +1100 (EST) Subject: Re: [PATCH] ppc: Add support for bigger page sizes than 4KB on PPC44x From: Benjamin Herrenschmidt To: Wolfgang Denk In-Reply-To: <20070313093754.4DE90353A9E@atlas.denx.de> References: <20070313093754.4DE90353A9E@atlas.denx.de> Content-Type: text/plain Date: Tue, 13 Mar 2007 14:54:27 +0100 Message-Id: <1173794067.24454.78.camel@localhost.localdomain> Mime-Version: 1.0 Cc: linuxppc-dev@ozlabs.org, Stefan Roese List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Tue, 2007-03-13 at 10:37 +0100, Wolfgang Denk wrote: > Dear Ben, > > in message <1173769934.24454.67.camel@localhost.localdomain> you wrote: > > > > - 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 :-) > > Will do that as soon as we have an arch/powerpc port for the 440SP / > 440SPe Ah great. I was thinking about working on 440GX after I'm back from the ski. (I have a Taishan board) We'll need to look into the MSI problem for SPe I suppose too... hopefully Michael should have a proper MSI core merged upstream soom (/me crosses fingers). > > - 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 > > 16 kB should work, but was not tested so far. From our RAID oriented > calculations it's not interesting. Fair enough. I still think it would be useful for other workloads to have that choice though :-) > We tried 256 kB, but kernel linking fails with a "Not enough room for > program headers" error message. We will investigate this ASAP, but at > the moment we have other priorities. [Any hints what might go wrong > are welcome.] 256K will not be doable without serious hacking afaik. Anything above 64K. You won't be able to run most userland apps for example as the sections are generally 64K aligned. > Agreed, but this obviously depends on the sort of application(s) > you're running. Definitely. Cheers, Ben.