Prioritize processes using Taskset

Almost every system has multiprocessors nowadays. You may require to run a process using 1 CPU or multiple CPUs. This functionality can be used by installing taskset.
Let's say you want to run firefox using one CPU. You'd run something like this:

taskset 0x00000001 firefox

For allowing firefox to use 2 CPUs replace 0x00000001 with 0x00000003

For allowing firefox to use all CPUs replace 0x00000001 with 0xFFFFFFFF

Taskset is really helpful when you want to put a limit on less important process, so that your important processes don't hang up while working 
Command Format:
taskset -p [mask] [pid]
Options
-p, --pid
    operate on an existing PID and not launch a new task
-c, --cpu-list
    specifiy a numerical list of processors instead of a bitmask. The list may contain multiple items, separated by comma, and ranges. For example, 0,5,7,9-11.
-h, --help
    display usage information and exit
-V, --version
    output version information and exit
Mask: specifies CPUs assigned. values: 0x00000001,  0x00000003,  0xFFFFFFFF

You can also retrieve the CPU affinity of an existing task:

taskset -p [pid]

References:
http://linux.die.net/man/1/taskset
http://www.serverwatch.com/tutorials/article.php/3915931/Using-Taskset-for-Priority-Tasks.htm