Make a CPU core sleep and run at 0%

Question

I have a code where I try to stress CPU cores. I want to run partial number of cores at 100% while the rest should run at 0%. The logic I've used for cores to run at 100% is:

#Pass the CPU core number as affinity
def loop(conn, affinity):
    proc = psutil.Process()
    proc_info = proc.pid
    msg = "Process ID: "+str(proc_info)+" CPU: "+str(affinity[0])
    conn.send(msg)
    conn.close()
    proc.cpu_affinity(affinity)    #Allocate a certain CPU core for this process
    while True:
        1*1

The cores executing this code run at 100%. I wrote another loop and am attaching the remaining cores to processing executing this loop:

def rest_cores(affinity, exec_time):
    proc = psutil.Process()
    proc.cpu_affinity(affinity)
    time.sleep(exec_time)

According to this logic, the cores should suspend execution for the exec_time and be at 0%. But the cores run at a higher percentage. How do I ensure that all the remaining cores are running at 0%?

Here is the full logic:

from multiprocessing import Process, Pipe
import os
import signal
import sys
import time
import psutil

def loop(conn, affinity):
    proc = psutil.Process()
    proc_info = proc.pid
    msg = "Process ID: "+str(proc_info)+" CPU: "+str(affinity[0])
    conn.send(msg)
    conn.close()
    proc.cpu_affinity(affinity)
    while True:
        1*1

def rest_cores(affinity, exec_time):
    proc = psutil.Process()
    proc.cpu_affinity(affinity)
    time.sleep(exec_time)


def cpu_stress():
    procs = []
    conns = []
    n_cpu = psutil.cpu_count(logical=True)
    proc_num = n_cpu//2                     #Half the cores will run at 100%
    
    for i in range(proc_num):               #Initial Half of the total cores
        parent_conn, child_conn = Pipe()
        p = Process(target=loop, args=(child_conn,[i]))
        p.start()
        procs.append(p)
        conns.append(parent_conn)

    for i in range(proc_num+1, n_cpu):      #Final half of total cores
        parent_conn, child_conn = Pipe()
        p = Process(target=rest_cores, args=([i], exec_time))
        p.start()
        procs.append(p)

    for conn in conns:
        try:
            print(conn.recv())
        except EOFError:
            continue

    time.sleep(exec_time)

    for p in procs:
        p.terminate()

cpu_stress()