cpu.py

import libvirt
import signal
import sys
import time

stats = []

def signal_handler(signal, frame):
    for stat in stats:
        print(",".join("%.2f" % x for x in stat))
    sys.exit(0)

conn = libvirt.open('qemu:///system')

dom = conn.lookupByName("archlinux")

signal.signal(signal.SIGINT, signal_handler)

start_clock_time = clock_time = time.time()
host_stats = dom.getCPUStats(0)
total_stats = dom.getCPUStats(1)[0]

while True:
    n_host_stats = dom.getCPUStats(0)
    n_total_stats = dom.getCPUStats(1)[0]
    n_clock_time = time.time()

    elapsed_time = n_clock_time - clock_time

    stat = [
        n_clock_time - start_clock_time,
        min((n_total_stats['cpu_time'] - total_stats['cpu_time']) / elapsed_time * 1e-7, 200)
    ]

    for i in range(len(host_stats)):
        stat.append(min((n_host_stats[i]['cpu_time'] - host_stats[i]['cpu_time']) / elapsed_time * 1e-7, 100))

    stats.append(stat)

    host_stats = n_host_stats
    total_stats = n_total_stats
    clock_time = n_clock_time

    time.sleep(2e-1)

graph.plot

set xlabel 'seconds'
set ylabel 'CPU usage'
set grid
set term png giant
set output 'graph.png'
set datafile separator ','                                                                                
plot 'stats.csv' using 1:2 title 'VM' with lines,\
     'stats.csv' using 1:3 title 'CPU0' with lines,\
     'stats.csv' using 1:4 title 'CPU1' with lines,\
     'stats.csv' using 1:5 title 'CPU2' with lines,\
     'stats.csv' using 1:6 title 'CPU3' with lines,\