taskset - set or retrieve a process's CPU affinity
taskset [options] mask command [argument...]
taskset [options] -p [mask] pid
The taskset command is used to set or retrieve the CPU affinity of a
running process given its pid, or to launch a new command with a
given CPU affinity. CPU affinity is a scheduler property that
"bonds" a process to a given set of CPUs on the system. The Linux
scheduler will honor the given CPU affinity and the process will not run on
any other CPUs. Note that the Linux scheduler also supports natural CPU
affinity: the scheduler attempts to keep processes on the same CPU as long as
practical for performance reasons. Therefore, forcing a specific CPU affinity
is useful only in certain applications.
The CPU affinity is represented as a bitmask, with the lowest
order bit corresponding to the first logical CPU and the highest order bit
corresponding to the last logical CPU. Not all CPUs may exist on a given
system but a mask may specify more CPUs than are present. A retrieved mask
will reflect only the bits that correspond to CPUs physically on the system.
If an invalid mask is given (i.e., one that corresponds to no valid CPUs on
the current system) an error is returned. The masks may be specified in
hexadecimal (with or without a leading "0x"), or as a CPU list
with the --cpu-list option. For example,
is processor #0,
is processors #0 and #1,
is processors #0 through #31,
is processors #1, #4, and #5,
is processors #0, #1, #2, and #6.
is processors #0, #2, #4, #6, #8 and #10. The suffix
":N" specifies stride in the range, for example 0-10:3 is
interpreted as 0,3,6,9 list.
When taskset returns, it is guaranteed that the given
program has been scheduled to a legal CPU.
Set or retrieve the CPU affinity of all the tasks
(threads) for a given PID.
Interpret mask as numerical list of processors
instead of a bitmask. Numbers are separated by commas and may include ranges.
For example: 0,5,8-11.
Operate on an existing PID and do not launch a new
Display version information and exit.
Display help text and exit.
The default behavior is to run a new command with a given affinity mask:
taskset mask command
You can also retrieve the CPU affinity of an existing task:
taskset -p pid
Or set it:
taskset -p mask pid
A user can change the CPU affinity of a process belonging to the same user. A
user must possess CAP_SYS_NICE to change the CPU affinity of a process
belonging to another user. A user can retrieve the affinity mask of any
Written by Robert M. Love.
Copyright © 2004 Robert M. Love. This is free software; see the source
for copying conditions. There is NO warranty; not even for MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE.