Paul E. McKenney wrote: > On Fri, May 07, 2010 at 04:11:42PM +0200, Pavel Machek wrote: >> Hi! >> >>> hotplug emulator: Abstract cpu register functions >>> >>> Abstract function arch_register_cpu and register_cpu, move the implementation >>> details to a sub function with prefix "__". >>> >>> each of the sub function has an extra parameter nid, it can be used to register >>> CPU under a fake NUMA node, it is a reserved interface for cpu hotplug emulation >>> (CPU PROBE/RELEASE) in x86. >> I don't get it. CPU hotplug can already be tested using echo 0/1 > >> online, and that works on 386. How is this different? "echo 0/1 > online" is logical cpu online/offline. The emulator intends to emulate physical add/remove of cpus. They cover different code path. You can get details of the terms via $KERN_SRC/Documentation/cpu-hotplug.txt. >> It seems to add some numa magic. Why is it important? In real world, numa affinity info of the cpus is required for physical cpu hotadd/remove , which finally affects related data structures and code path. Emulator need the ability to emulate it. > My guess is that he wants to test the software surrounding NUMA on a > non-NUMA (or different-NUMA) machine, perhaps in order to shake out bugs > before the corresponding hardware is available. This is one of the purposes. Auto tests and debugging all can get benefits from such emulation. -haicheng _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
