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Python | os.sched_setaffinity() method

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OS module in Python provides functions for interacting with the operating system. OS comes under Python’s standard utility modules. This module provides a portable way of using operating system dependent functionality.

os.sched_setaffinity() method in Python is used to set the CPU affinity mask of a process indicated by the specified process id. A process’s CPU affinity mask determines the set of CPUs on which it is eligible to run.

Note: This method is only available on some UNIX platforms.

Syntax: os.sched_setaffinity(pid, mask)

Parameter:
pid: The process id of the process whose CPU affinity mask is to be set required. Process’s CPU affinity mask determines the set of CPUs on which it is eligible to run.
A pid of 0 represents the calling process.
mask: An iterable of integers representing the set of CPUs to which the process should be restricted.

Return Type: This method does not return any value.

Code: Use of os.sched_setaffinity() method




# Python program to explain os.sched_setaffinity() method  
  
# importing os module 
import os
  
# Get the number of CPUs
# in the system
# using os.cpu_count() method
print("Number of CPUs:", os.cpu_count())
  
# Get the set of CPUs
# on which the calling process
# is eligible to run. using
# os.sched_getaffinity() method
# 0 as PID represents the
# calling process
pid = 0
affinity = os.sched_getaffinity(pid)
  
# Print the result
print("Process is eligible to run on:", affinity)
  
  
# Change the CPU affinity mask
# of the calling process
# using os.sched_setaffinity() method
  
# Below CPU affinity mask will
# restrict a process to only
# these 2 CPUs (0, 1) i.e process can
# run on these CPUs only
affinity_mask = {0, 1}
pid = 0
os.sched_setaffinity(0, affinity_mask)
print("CPU affinity mask is modified for process id % s" % pid) 
  
  
# Now again, Get the set of CPUs
# on which the calling process
# is eligible to run.
pid = 0
affinity = os.sched_getaffinity(pid)
  
# Print the result
print("Now, process is eligible to run on:", affinity)


Output:

Number of CPUs: 4
Process is eligible to run on: {0, 1, 2, 3}
CPU affinity mask is modified for process id 0
Now, process is eligible to run on: {0, 1}

References:



Last Updated : 02 Nov, 2021
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