From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e34.co.us.ibm.com (e34.co.us.ibm.com [32.97.110.152]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "e34.co.us.ibm.com", Issuer "Equifax" (verified OK)) by ozlabs.org (Postfix) with ESMTP id 1F449DDE1F for ; Sat, 8 Dec 2007 09:18:54 +1100 (EST) Received: from d03relay04.boulder.ibm.com (d03relay04.boulder.ibm.com [9.17.195.106]) by e34.co.us.ibm.com (8.13.8/8.13.8) with ESMTP id lB7MIpjB027903 for ; Fri, 7 Dec 2007 17:18:51 -0500 Received: from d03av02.boulder.ibm.com (d03av02.boulder.ibm.com [9.17.195.168]) by d03relay04.boulder.ibm.com (8.13.8/8.13.8/NCO v8.7) with ESMTP id lB7MIpgw121218 for ; Fri, 7 Dec 2007 15:18:51 -0700 Received: from d03av02.boulder.ibm.com (loopback [127.0.0.1]) by d03av02.boulder.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id lB7MIob1021699 for ; Fri, 7 Dec 2007 15:18:50 -0700 Message-ID: <4759C6C5.2000100@linux.vnet.ibm.com> Date: Sat, 08 Dec 2007 03:48:45 +0530 From: Balbir Singh MIME-Version: 1.0 To: Kumar Gala Subject: Re: [PATCH] Fake NUMA emulation for PowerPC References: <20071207211425.10223.91240.sendpatchset@balbir-laptop> <20071207212817.GA391@lixom.net> <4759BCA2.1020809@linux.vnet.ibm.com> <975B5B2B-C1F3-4021-9AE2-8873FFE1BDEC@kernel.crashing.org> <4759C548.6030304@linux.vnet.ibm.com> <9AEDD952-7F20-471C-9A82-B6F3254BC869@kernel.crashing.org> In-Reply-To: <9AEDD952-7F20-471C-9A82-B6F3254BC869@kernel.crashing.org> Content-Type: text/plain; charset=ISO-8859-1 Cc: Olof Johansson , linuxppc-dev@ozlabs.org, LKML Reply-To: balbir@linux.vnet.ibm.com List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Kumar Gala wrote: > > On Dec 7, 2007, at 4:12 PM, Balbir Singh wrote: > >> Kumar Gala wrote: >>> >>> On Dec 7, 2007, at 3:35 PM, Balbir Singh wrote: >>> >>>> Olof Johansson wrote: >>>>> Hi, >>>>> >>>>> On Sat, Dec 08, 2007 at 02:44:25AM +0530, Balbir Singh wrote: >>>>> >>>>>> Comments are as always welcome! >>>>> >>>>> Care to explain what this is useful for? (Not saying it's a stupid >>>>> idea, >>>>> just wondering what the reason for doing it is). >>>>> >>>> >>>> In my case, I use it to test parts of my memory controller patches >>>> on an >>>> emulated NUMA machine. I plan to use it to test out page migration >>>> across nodes. >>> >>> Can you explain that further. I'm still not clear on why this is >>> useful. >>> >>> - k >> >> Sure. In my case I need to emulate NUMA nodes to do some NUMA specific >> testing. The memory controller I've written has some interesting data >> structures like per node, per zone LRU lists. To be able to test those >> features on a non-numa box is a problem, since we get just the default >> node. > > Maybe I'm missing something, what do you mean by memory controller > you've written? (I'm use to the term 'memory controller' meaning the > actual RAM control). > Ah! that explains the disconnect. If you look at the latest -mm tree. We have a memory controller under control groups, we use it to control how much memory a group of process can access at a time. >> To be able to test the memory controller under NUMA, I use fake NUMA >> nodes. x86-64 has a similar feature, the code I have here is the >> simplest I could come up with for PowerPC. >> >> I just thought of another very interesting use case, it can be used to >> split up the zone's lru lock which is highly contended. > > - k -- Warm Regards, Balbir Singh Linux Technology Center IBM, ISTL