Since an explanation could not yet be found for this phenomenon. I have plotted two graphs to show the effect.
https://www.dropbox.com/s/5e8xrrctu0rcwx3/CPU%20scaling%20%20-%20continuous%20vs%20increasing%20from%201.png?dl=0 https://www.dropbox.com/s/txpkb8k6mpyexv8/CPU%20scaling%20-%20increase%20from%201.png?dl=0 The first graph shows the VM CPU resize time (y axis) vs number of vCPUs (x axis) of continuous (blue) and resize from a VM with 1 vCPU (green) scenarios.The second graph shows the VM CPU resize time (y axis) vs number of vCPUs (x axis), when resized from a VM with 1 vCPU at each step (The green line in first graph). The error bars show the standard error of the gathered values at each step, as I did resize multiple times to get a mean value. Can anyone give an explanation for this? > On 26 Jul 2016, at 11:30, Chathura M. Sarathchandra Magurawalage > <77.chath...@gmail.com> wrote: > > Thanks Tomas. > > Yes you are right but that will only happen when you resize disk at each > step. But when I increased CPU other resource were kept fixed. So in This > case, it won’t be copying bigger disk over each time. > > >> On 26 Jul 2016, at 08:45, Tomas Vondra <von...@czech-itc.cz> wrote: >> >> Chathura M. Sarathchandra Magurawalage <77.chathura@...> writes: >> >>> >>> Hi, >>> >>> Does anyone know the reason for VM resizing time to increase faster if you >> continuously increase CPU or DISK >>> resources by +1 (e.g. 1-2, 2-3, 3-4, 4-5). Whereas, when you increase from >> 1 to any of +1/+2/+3/+4…..+n >>> (e.g. 1-2, 1,3, 1-4, 1-5), the VM resize time still increases at each >> step, but it takes less time in >>> comparison to the former method. Can anyone give an explanation for this? >>> >> >> Hi! >> If I'm correct, the resize operation stops the VM, migrates it to another >> computed node and starts it with another configuration there. >> So if you have your VM running on local storage, moreover raw local storage, >> you will be copying a bigger disk over each time. Otherwise, it should not >> matter. Am I correct about your configuration? >> Tomas >> _______________________________________________ >> Mailing list: http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack >> Post to : openstack@lists.openstack.org >> Unsubscribe : http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack > _______________________________________________ Mailing list: http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack Post to : openstack@lists.openstack.org Unsubscribe : http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack
