RE: [8/8,v3] NUMA Hotplug Emulator: documentation

Li, Haicheng
2010-11-21T15:17:21Z

Américo Wang wrote:
> On Wed, Nov 17, 2010 at 10:08:07AM +0800, shaohui.zheng@intel.com
> wrote:
>> +2) CPU hotplug emulation:
>> +
>> +The emulator reserve CPUs throu grub parameter, the reserved CPUs
>> can be +hot-add/hot-remove in software method, it emulates the
>> process of physical +cpu hotplug. +
>> +When hotplug a CPU with emulator, we are using a logical CPU to
>> emulate the CPU +socket hotplug process. For the CPU supported SMT,
>> some logical CPUs are in the +same socket, but it may located in
>> different NUMA node after we have emulator. +We put the logical CPU
>> into a fake CPU socket, and assign it an unique +phys_proc_id. For
>> the fake socket, we put one logical CPU in only. + + - to hide CPUs
>> + - Using boot option "maxcpus=N" hide CPUs
>> + N is the number of initialize CPUs
>> + - Using boot option "cpu_hpe=on" to enable cpu hotplug emulation
>> + when cpu_hpe is enabled, the rest CPUs will not be
>> initialized + + - to hot-add CPU to node
>> + $ echo nid > cpu/probe
>> +
>> + - to hot-remove CPU
>> + $ echo nid > cpu/release
>> +
>
> Again, we already have software CPU hotplug,
> i.e. /sys/devices/system/cpu/cpuX/online.

online here is just for logical CPU online. what we're achieving here is to emulate physical CPU hotadd.

-haicheng