affinity: Process Affinity

Description Usage Arguments Details References Examples

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

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Arguments

cpus

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

Details

Setting a process afinity 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)](http://man7.org/linux/man-pages/man2/sched_setaffinity.2.html)

Examples

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

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

# Reset
setaffinity()
getaffinity()

## End(Not run)

jeroenooms/RAppArmor documentation built on May 17, 2017, 6:16 p.m.