On Wed, Nov 17, 2010 at 10:50:07AM -0800, Dave Hansen wrote: > On Wed, 2010-11-17 at 10:08 +0800, shaohui.zheng@xxxxxxxxx wrote: > > And more we make it friendly, it is possible to add memory to do > > > > echo 3g > memory/probe > > echo 1024m,3 > memory/probe > > > > It maintains backwards compatibility. > > > > Another format suggested by Dave Hansen: > > > > echo physical_address=0x40000000 numa_node=3 > memory/probe > > > > it is more explicit to show meaning of the parameters. > > The other thing that Greg suggested was to use configfs. Looking back > on it, that makes a lot of sense. We can do better than these "probe" > files. > > In your case, it might be useful to tell the kernel to be able to add > memory in a node and add the node all in one go. That'll probably be > closer to what the hardware will do, and will exercise different code > paths that the separate "add node", "then add memory" steps that you're > using here. > > For the emulator, I also have to wonder if using debugfs is the right > was since its ABI is a bit more, well, _flexible_ over time. :) There will be a lot of problems which need to solve if we decide to use configfs or debugfs. I have no good method to solve these problems, so I want to listen some advices. 1) How to design the probe interace I can not find a good method with configfs to replace current memory/probe interface. As we know, A configfs config_item is created via an explicit userspace operation mkdir. when we add a memory section, we need to convert it to an mkdir action. the following implementation is the possible solution. node/memory hotplug: /configfs/node when we hotadd node, we can create dir with command: mkdir /configfs/node/nodeX And export a probe interface /configfs/node/nodeX/probe, we can use this interface to hot-add memory section to this node. after memory hot-add with the probe interface, there should be some memory entries for each memory section under this directories. cpu hotplug: /configfs/cpu/ to hot-add a cpu mkdir /configfs/cpu/cpuX to hot-remove a CPU rmdir /configfs/cpu/cpuX I did not whether it is the expected interface on configfs. 2) co-existence for sysfs and configfs If we keep both interfaces, thing becomes complicated. when we hot-add memory/cpu thru sysfs, we should create the sysfs entrie for it, and we should also create the configfs entries for it. Vice versa, when we hot-add/remove cpu/memory thru configfs, we should maintain the changes on sysfs, too. it becomes very complicated after we have both configfs & sysfs interface, and we should not get them together, we need to get it simple. the purpose of hotplug emulator is providing a possible solution for cpu/memory hotplug testing, the interface upgrading is not part of emulator. Let's forget configfs here. -- Thanks & Regards, Shaohui -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom policy in Canada: sign http://dissolvethecrtc.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>