set_cpu_usage

set_cpu_usage.py

import sys
import random
import time

TARGET = -1

ADJUST_THRESHOLD = 100
CNT_MIN = 0
SLP_MIN = 1
SLP_MAX = 10

cnt_top = 0
slp = 1

cnt = 0
adjust_cnt = 0

last_cpu_total = 0L
last_cpu_idle = 0L

def get_cpu_usage():
    global last_cpu_total
    global last_cpu_idle
    f = open('/proc/stat', 'r')
    cpu_line = f.readline()
    f.close()
    values = cpu_line.split()[1:-1]
    total = 0L
    for value in values:
        total += long(value)
    idle = long(values[3])
    result = 101

    total_delta = total - last_cpu_total
    idle_delta = idle - last_cpu_idle
    if last_cpu_total != 0 and total_delta >= 0:
        if idle_delta == 0:
            result = 0
        else:
            result = int(100 * idle_delta / total_delta)
    last_cpu_total = total
    last_cpu_idle = idle
    return 100 - result

def adjust():
    usage = get_cpu_usage()
    if usage < 0:
        return
    global cnt_top
    global slp
    delta = usage - TARGET
    if delta < 0:
        delta = -delta
    delta_per = float(delta) / TARGET
    print ('usage: ' + str(usage) + ', cnt_top: ' + str(cnt_top) + ', slp: ' + str(slp) + ', delta_per: ' + str(delta_per))
    # cnt_incr
    cnt_incr = int(delta_per * 500)
    # cnt_decr
    cnt_decr = int(delta_per * 500)
    # slp_incr
    slp_incr = 1
    # slp_decr
    slp_decr = 1
    # ensures at least 1
    if cnt_incr < 0:
        cnt_incr = 1
    if cnt_decr == 0:
        cnt_decr = 1
    if slp_incr == 0:
        slp_incr = 1
    if slp_decr == 0:
        slp_decr = 1
    if usage > TARGET:
        # cpu too high
        # need to decrease cnt or increase slp
        if cnt_top > (cnt_decr + CNT_MIN):
            cnt_top -= cnt_decr
        elif cnt_top > CNT_MIN:
            cnt_top = CNT_MIN
        elif slp + slp_incr < SLP_MAX:
            slp += slp_incr
        else:
            slp = SLP_MAX
    elif usage < TARGET:
        # cpu too low
        # need to increase cnt or decrease slp
        if slp > (slp_decr + SLP_MIN):
            slp -= slp_decr
        elif slp > SLP_MIN:
            slp = SLP_MIN
        else:
            cnt_top += cnt_incr
    print ('update to: cnt_top: ' + str(cnt_top) + ', slp: ' + str(slp))

TARGET = int(sys.argv[1])
print ('the target cpu usage is ' + str(TARGET) + '%')

while True:
    random.randint(1,101)
    if cnt > cnt_top:
        cnt = 0
        time.sleep(float(slp) / 1000)
        if adjust_cnt > int(ADJUST_THRESHOLD / slp):
            adjust_cnt = 0
            adjust()
        adjust_cnt += 1
    cnt += 1