<cpu number>,...,<cpu number>
<cpu number>-<cpu number>
(must be a positive range in ascending order) or a mixture
<cpu number>,...,<cpu number>-<cpu number>
This option can be used to specify one or more CPUs to isolate from the general SMP balancing and scheduling algorithms. You can move a process onto or off an "isolated" CPU via the CPU affinity syscalls or cpuset.
<cpu number> begins at 0 and the maximum value is "number of CPUs in system - 1".
This option is the preferred way to isolate CPUs. The alternative -- manually setting the CPU mask of all tasks in the system -- can cause problems and suboptimal load balancer performance.
Taken from /usr/share/doc/kernel-doc-2.6.32/Documentation/kernel-parameters.txt