On Thu, 2 Dec 2010, Shaohui Zheng wrote: > > > From: Shaohui Zheng <shaohui.zheng@xxxxxxxxx> > > > > > > Implement a debugfs inteface /sys/kernel/debug/mem_hotplug/probe for meomory hotplug > > > emulation. it accepts the same parameters like > > > /sys/devices/system/memory/probe. > > > > > > > NACK, we don't need two interfaces to do the same thing. > > You may not know the background, the sysfs memory/probe interface is a general > interface. Even through we have a debugfs interface, we should still keep it. > > For test purpose, the sysfs is enough, according to the comments from Greg & Dave, > we create the debugfs interface. > I doubt either Greg or Dave suggested adding duplicate interfaces for the same functionality. The difference is that we needed to add the add_node interface in a new mem_hotplug debugfs directory because it's only useful for debugging kernel code and, thus, doesn't really have an appropriate place in sysfs. Nobody is going to use add_node unless they lack hotpluggable memory sections in their SRAT and want to debug the memory hotplug callers. For example, I already wrote all of this node hotplug emulation stuff when I wrote the node hotplug support for SLAB. Memory hotplug, however, does serve a non-debugging function and is appropriate in sysfs since this is how people hotplug memory. It's an ABI that we can't simply remove without deprecation over a substantial period of time and in this case it doesn't seem to have a clear advantage. We need not add special emulation support for something that is already possible for real systems, so adding a duplicate interface in debugfs is inappropriate. -- 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>