Re: virsh dominfo does not show correct cpuTime

[changqian zuo <zuochangqian@xxxxxxxxx>]

I was getting vCPU use time outside of guest with libvirt-python API, and them calculate utilization with (cpuTime2 - cpuTime1) / (t2 - t1). I was not doing this inside the guest os.

2015-07-24 15:09 GMT+08:00 2020human <human2020@xxxxxx>:

You calculate is vCPU use time not utilization。

use_time/total_cpu_time  is utilization。

total_cpu_time=`cat /proc/stat |sed -n '1p'|awk '{ print sum=$2+$3+$4+$5+$6+$7+$8+$9+$10}'`

------------------ 原始邮件 ------------------

发件人: "changqian zuo";<zuochangqian@xxxxxxxxx>;

发送时间: 2015年7月24日(星期五) 中午1:51

收件人: "libvirt-users"<libvirt-users@xxxxxxxxxx>;

主题:  virsh dominfo does not show correct cpuTime

Hi,

I am doing some domain resource monitoring work. I use

  cat /dev/urandom | md5sum

to simulate vCPU load and write a script to calculate vCPU utilization. It seems all good at the beginning. After I abort the ``cat ... md5sum`` command in domain, I see some strange data as below:

CPU time: 8410960000000

CPU util: 99.8410609331%

CPU time: 8411970000000

CPU util: 100.843672381%

CPU time: 8412380000000

CPU util: 40.9336949531%

CPU time: 8412440000000

CPU util: 5.9899303915%

CPU time: 8412440000000

CPU util: 0.0%

CPU time: 8412490000000

CPU util: 4.99165856007%

CPU time: 8412490000000

CPU util: 0.0%

CPU time: 8412490000000

CPU util: 0.0%

CPU time: 8412570000000

CPU util: 7.987195515%

CPU time: 8412570000000

CPU util: 0.0%

CPU time: 8412590000000

CPU util: 1.99668576091%

CPU time: 8412670000000

CPU util: 7.98700539474%

CPU time: 8412720000000

CPU util: 4.99167281754%

CPU time: 8412780000000

CPU util: 5.98888552548%

Looking at those 0.0% lines. Strange, though the guest is running, cpuTime does not increase. How can this happen? Any one helps? Thanks.

Host information:

- CentOS Linux release 7.0.1406 (Core)

- libvirt 1.2.8

- qemu-kvm-rhev 2.1.2

----- python script to capture cpu domain usage ----

import libvirt

import time

conn = libvirt.openReadOnly("qemu:///system")

dom = conn.lookupByName('cpu-test')

last_time = time.time()

last_cpu_time = dom.info()[4]

while True:

  time.sleep(1)

  this_time = time.time()

  dom_info = dom.info()

  print "CPU time: %s" % dom_info[4]

  print "CPU util: %s%%" % ((dom_info[4] - last_cpu_time) / ((this_time - last_time) * 10000000))

  last_cpu_time = dom_info[4]

  last_time = this_time

----------------------------- end -----------------------------

_______________________________________________
libvirt-users mailing list
libvirt-users@xxxxxxxxxx
https://www.redhat.com/mailman/listinfo/libvirt-users