On Mon, 22 Nov 2010, Shaohui Zheng wrote: > > and then creating a new 128M node at runtime: > > > > # echo 128M@0x80000000 > /sys/devices/system/memory/add_node > > On node 1 totalpages: 0 > > init_memory_mapping: 0000000080000000-0000000088000000 > > 0080000000 - 0088000000 page 2M > > For cpu/memory physical hotplug, we have the unique interface probe/release, > it is the _standard_ interface, it is not only for x86, ppc use the the interface > as well. For node hotplug, it should follow the rule. > > You are creating a new interface /sys/devices/system/memory/add_node to add both > memory and node, you are just trying to create DUPLICATED feature with the > memory probe interface, it breaks the rule. > It's not duplicated, the function of add_node is distinct since it maps the added memory to a node that wasn't previously defined (for the x86 case, defined by the SRAT). I think this is better than an additional abstraction layer that remaps memory to nodes above what the BIOS has defined, and there's nothing architecture specific about add_node; if an arch can do probe then it can use this new interface. > I did NOT see the feature difference with our emulator patch http://lkml.org/lkml/2010/11/16/740, > you pick up a piece of feature from emulator, and create an other thread. You > are trying to replace the interface with a new one, which is not recommended. > the memory probe interface is already powerful and flexible enough after apply > our patch. What's more important, it keeps the old directives, and it maintains > backwards compatibility. > This achieves the same goal in a much cleaner and generic way. It doesn't replace anything that currently sits in the kernel, instead it competes directly with your model for node hotplug emulation. > Add a memory section(128M) to node 3(boots with mem=1024m) > > echo 0x40000000,3 > memory/probe > > 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. > My patch doesn't break backwards compatibility, it adds a new debugfs file that allows you to test node hotplug. > Another format suggested by Dave Hansen: > > echo physical_address=0x40000000 numa_node=3 > memory/probe > > we should not need duplicated interface /sys/devices/system/memory/add_node here. > We don't need to define a node id, we only need to ensure that a possible node is not yet online and use it; we don't gain anything by trying to hotplug node ids in a sparse or interleaved way (although it is certainly possible with a combination of my patch and CONFIG_MEMORY_HOTREMOVE). -- 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>