affinity {RAppArmor}

Process Affinity

Description

Get/set the process's CPU affinity mask. The affinity mask binds the process to specific core(s) within the machine. Not supported on all systems, has_affinity() shows if this is available.

Usage

setaffinity(cpus = 1:ncores())

getaffinity_count()

getaffinity()

has_affinity()

ncores()

Arguments

cpus

Which cpu cores to bind to: vector of integers between 1 and ncores()

Details

Setting a process affinity allows for restricting the process to only use certain cores in the machine. The cores are indexed by the operating system as 1 to ncores(). Calling setaffinity() with no arguments resets the process to use any of the available cores.

Note that setaffinity is different from setting r_limit values in the sense that it is not a one-way process. An unprivileged user can change the process affinity to any value. In order to 'lock' an affinity value, one would have to manipulate Linux capability value for CAP_SYS_NICE.

References

SCHED_SETAFFINITY(2)

Examples

## Not run: 
# Current affinity
ncores()
getaffinity()
getaffinity_count()

# Restrict process to core number 1.
setaffinity(1)
getaffinity()

# Reset
setaffinity()
getaffinity()

## End(Not run)