How can I set the processor affinity of a process on Linux?
I have used taskset for this. If you have taskset installed, something like:
taskset -cp 0,2 45678
would set the process with id 45678 to have an affinity to cpus 1 and 3.
taskset: failed to execute -p: No such file or directory. Apr 7, 2020 at 7:02
tasksetchanged it's params since I originally posted this?– kbyrdApr 7, 2020 at 14:57
Syntax seems to be
taskset -pc 0,2 45678– CameronSep 28, 2020 at 12:54
fixed, thanks. Actually tested on a cmdline. As of now.
-cpis correct– kbyrdSep 28, 2020 at 15:11
1Usage in the form
taskset -pc cpulist pide. g.
taskset -pc 0,3,7-11 700is actually included in compiled-in help (tested on taskset from util-linux 2.32.1 and 2.29.2). Both
-pcwork for me.– d.c.Feb 5, 2021 at 14:04
Inside the process, the call would be
sched_setaffinity(), or for pthreads stuff,
On a related note, if you're worrying about CPU affinity of your program, it may be worthwhile to pay attention to how it's doing memory allocation as well. Larger systems with memory attached to more than one controller (i.e. multiple CPU sockets, each with their own) will have variable latency and bandwidth between different CPU-memory pairs. You'll want to look into NUMA affinity as well, using the
numactl command or the system calls that it works with. One program I worked on got a 10% performance improvement from this.
You need to install
schedutils (Linux scheduler utilities).
I have use it on my Ubuntu Desktop.
taskset -c 1-3 ./a.out arg1 arg2
a.out process with given arguments and affinity set to processors 1, 2 or 3 (zero based).
Here is a minimal C test program that can be used to see it in action: https://stackoverflow.com/questions/10490756/how-to-use-sched-getaffinity-and-sched-setaffinity-in-linux-from-c/50117787#50117787