Messages in this thread | | | Date | Thu, 18 Nov 2010 13:24:52 -0800 (PST) | From | David Rientjes <> | Subject | Re: [2/8,v3] NUMA Hotplug Emulator: infrastructure of NUMA hotplug emulation |
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On Thu, 18 Nov 2010, Shaohui Zheng wrote:
> in our draft patch, we re-setup nr_node_ids when CONFIG_ARCH_MEMORY_PROBE enabled > and mem=XXX was specified in grub. we set nr_node_ids as MAX_NUMNODES + 1, because > we do not know how many nodes will be hot-added through memory/probe interface. > it might be a little wasting of memory. >
nr_node_ids need not be set to anything different at boot, the MEM_GOING_ONLINE callback should be used for anything (like the slab allocators) where a new node is introduced and needs to be dealt with accordingly; this is how regular memory hotplug works, we need no additional code in this regard because it's emulated. If a subsystem needs to change in response to a new node going online and doesn't as a result of using your emulator, that's a bug and either needs to be fixed or prohibited from use with CONFIG_MEMORY_HOTPLUG.
(See the MEM_GOING_ONLINE callback in mm/slub.c, for instance, which deals only with the case of node hotplug.)
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