From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mgw3.sony.co.jp (MGW3.Sony.CO.JP [137.153.0.15]) by ozlabs.org (Postfix) with ESMTP id 783A767D4E for ; Mon, 13 Nov 2006 13:05:19 +1100 (EST) Received: from mail7.sony.co.jp (localhost [127.0.0.1]) by mail7.sony.co.jp (R8/Sony) with ESMTP id kAD25HmD006049 for ; Mon, 13 Nov 2006 11:05:17 +0900 (JST) Received: from mailgw01.scei.sony.co.jp (mailgw01.scei.sony.co.jp [43.27.73.7]) by mail7.sony.co.jp (R8/Sony) with SMTP id kAD25G0l006029 for ; Mon, 13 Nov 2006 11:05:16 +0900 (JST) Message-ID: <4557D2D2.20004@am.sony.com> Date: Sun, 12 Nov 2006 18:05:06 -0800 From: Geoff Levand MIME-Version: 1.0 To: michael@ellerman.id.au Subject: Re: [PATCH 13/16] powerpc: add ps3 platform lpar addressing References: <4554DB14.3070900@am.sony.com> <20061111112847.GD24288@lst.de> <1163292316.4982.240.camel@localhost.localdomain> <1163378514.7410.16.camel@localhost.localdomain> In-Reply-To: <1163378514.7410.16.camel@localhost.localdomain> Content-Type: text/plain; charset=UTF-8 Cc: Paul Mackerras , linuxppc-dev@ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Michael Ellerman wrote: > On Sun, 2006-11-12 at 11:45 +1100, Benjamin Herrenschmidt wrote: >> On Sat, 2006-11-11 at 12:28 +0100, Christoph Hellwig wrote: >> > On Fri, Nov 10, 2006 at 12:03:32PM -0800, Geoff Levand wrote: >> > > Adds some needed bits for a config option PS3PF_USE_LPAR_ADDR that disables >> > > the ps3pf lpar address translation mechanism. This is a currently needed >> > > workaround for limitations in the design of the spu support. >> > >> > So make the code do the sane thing and don't put the config in the >> > kernel tree. >> >> Well... I'd like to keep the option for a little while. >> >> There are performances issues with sparsemem the way it's used by >> ps3pf.. the problem is that the memory map looks like you get a bunch of >> memory at 0 (the RMO, not sure exactly how much in practice) and the >> rest in a chunk all the way up the 48 bits or so max physical space. >> >> So sparsemem ends up with an enormous mapping only populated at the very >> beginning and the very end. >> >> Thus, I'd like Geoff to keep the option of doing the manual translation >> in the hash code for now until I finally get some HW and thus can do >> some measurements, and possibly figure out a nicer way to deal with >> that. > > I haven't read the ps3 code very carefully, but at first glance it > struck me that it has a similar problem to iSeries. It might be worth > seeing if the iSeries mschunks_map gunk can help (see > include/asm-powerpc/abs_addr.h) Yes, it is essentially the same as iSeries, but since the current spu code sets up the spu local stores as chunks of sparse memory, I still need this for those. To fix it properly the spu code needs to be re-worked, and Ben said he plans to do some work there. At that time I will reconsider how to manage the mem regions. As Christoph says though, this doesn't really need to be exposed as a config option, but I wanted to include it for anyone that wanted to experiment with it. If you don't use spus you can save about 256KB with this option. -Geoff