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Message-ID: <4759C6C5.2000100@linux.vnet.ibm.com> Date: Sat, 08 Dec 2007 03:48:45 +0530 From: Balbir Singh <balbir@...ux.vnet.ibm.com> To: Kumar Gala <galak@...nel.crashing.org> CC: Olof Johansson <olof@...om.net>, linuxppc-dev@...abs.org, LKML <linux-kernel@...r.kernel.org> Subject: Re: [PATCH] Fake NUMA emulation for PowerPC 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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