On 2017-12-20 03:14 AM, Jaze Lee wrote: > Hello, > We use ceilometer newton, and also master calculates cpu same as newton. > It is in > https://github.com/openstack/ceilometer/blob/master/ceilometer/compute/virt/libvirt/inspector.py#L183 > > I test with a two vcpu vm, and find using this method as line 183 > we can not get cpu util 100, always 50 or 52. > > The test script is here(run on compute node, and there is only one vm) > #!/bin/bash > > cpu_time_begin=`virsh domstats --cpu-total | grep cpu.time| awk -F > '=' '{print $2}'` > sleep 1 > cpu_time_end=`virsh domstats --cpu-total | grep cpu.time| awk -F '=' > '{print $2}'` > > cpu_util=$(((cpu_time_end - cpu_time_begin) * 100 / 10**9)) > echo "cpu util is ", $cpu_util > > The output will be 100 or 101, if we divide cpu_util with core number, > then we definitely get 50. But in the vm we watch with top and find > all core is 99%. > > Can someone tell me why we only use cpu_time here? May be we should > add cpu.user and cpu.system? It is insane only get 50% when the vm is > totally 100%.... >
does adding cpu.user and cpu.system make sense or are you just adding random numbers in hopes it gets you to right number? :P i'm not a libvirt/qemu dev but it seems cpu.system is already part of cpu.time[1] if you look further into the code, you should see that the agent tries to first use vcpu.*.time to build more accurate cpu.time value. if you look at patch[3], it should give you more information as to why and what requirements you need. [1] https://stackoverflow.com/questions/40468370/what-does-cpu-time-represent-exactly-in-libvirt [2] https://github.com/openstack/ceilometer/blob/master/ceilometer/compute/virt/libvirt/inspector.py#L175-L176 [3] https://github.com/openstack/ceilometer/commit/a4ec0911a3ed4137a1c832fbd7c8fee80c7d4601 cheers, -- gord __________________________________________________________________________ OpenStack Development Mailing List (not for usage questions) Unsubscribe: openstack-dev-requ...@lists.openstack.org?subject:unsubscribe http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
