The reason is that there are many things such as interrupt affinity,
memory affinity factor that can have a big impact on the test.

Before this patch, the first domain level is unchangeable after
creation.

This patch introduce the 'cpu.rebuild_affinity_domain' to dynamically
reconfigure all domain levels.

Typical use cases:

echo $cpu_id > cpu.rebuild_affinity_domain

The cpu_id means which cpu we want to set first level.

If we set cpu_id = 34, we can see some change like:

 ----------------                       -----------------
| level 0 (0-31) |                     | level 0 (32-63) |
 ----------------                       -----------------
         v                                   v
 -------------------                    ------------------
|  level 1 (0-63)   |                  |  level 1 (0-63)  |
 -------------------                    ------------------
           v                  -->              v
 ---------------------                  --------------------
|   level 2 (0-95)    |                |   level 2 (0-95)   |
 ---------------------                  --------------------
             v                                   v
 ------------------------               ----------------------
|    level 3 (0-127)     |             |    level 3 (0-127)   |
 ------------------------               ----------------------

There are number of constraints on the rebuild feature:

1. Only rebuild domain while auto mode disabled.
   (cpu.dynamic_affinity_mode == 1)
2. Only rebuild on active and housekeeping cpu.
   (Offline and isolate CPUs are forbidden)
3. This file is write only.