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# Copyright (c) 2006-2025. The SimGrid Team. All rights reserved.
#
# This program is free software; you can redistribute it and/or modify it
# under the terms of the license (GNU LGPL) which comes with this package.
"""
This example shows how to simulate a non-linear resource sharing for CPUs.
"""
import functools
import sys
from simgrid import Actor, Engine, NetZone, Host, this_actor
def runner():
computation_amount = this_actor.get_host().speed
n_task = 10
this_actor.info("Execute %d tasks of %g flops, should take %d second in a CPU without degradation. \
It will take the double here." % (n_task, computation_amount, n_task))
tasks = [this_actor.exec_init(computation_amount).start()
for _ in range(n_task)]
this_actor.info("Waiting for all tasks to be done!")
for task in tasks:
task.wait()
this_actor.info("Finished executing. Goodbye now!")
def cpu_nonlinear(host: Host, capacity: float, n: int) -> float:
""" Non-linear resource sharing for CPU """
# emulates a degradation in CPU according to the number of tasks
# totally unrealistic but for learning purposes
capacity = capacity / 2 if n > 1 else capacity
this_actor.info("Host %s, %d concurrent tasks, new capacity %f" %
(host.name, n, capacity))
return capacity
def load_platform(e:Engine):
""" Create a simple 1-host platform """
zone = e.netzone_root
runner_host = zone.add_host("runner", 1e6)
runner_host.set_sharing_policy(
Host.SharingPolicy.NONLINEAR, functools.partial(cpu_nonlinear, runner_host))
runner_host.seal()
zone.seal()
# create actor runner
runner_host.add_actor("runner", runner)
if __name__ == '__main__':
e = Engine(sys.argv)
# create platform
load_platform(e)
# runs the simulation
e.run()
# explicitly deleting Engine object to avoid segfault during cleanup phase.
# During Engine destruction, the cleanup of std::function linked to non_linear callback is called.
# If we let the cleanup by itself, it fails trying on its destruction because the python main program
# has already freed its variables
del e
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