Assuming you are on KVM...total number of Shares = total number of Mhz (cores * Mhz) / cpuOverprovisioningFactor - cpu shares get changed (after changing cpu overprovisioning) only when you stop and start an existing VM. So i.e. 2 vCPU of 2000 MHz VM, with CPU overprovisioning of 2 will get (2*2000)/2= 2000 CPU shares
In that regards, there are no "reservation" specifically, but cpu shares are "engaged" only when there is shortage of CPU cycles on the host, otherwise is not applicable. CPU cap has been implemented for KVM only in 4.12 (if not mistaken), but in general even if CPU cap has been set on the offerings, if changing cpu overprovisioning factor, cpu cap will NOT change on hypervisor side (can confirm for XS and VMware but expect same for KVM in 4.12) - i.e. it always stays the same. Hope that helps, Andrija On Sun, Jul 7, 2019, 18:04 Fariborz Navidan <mdvlinqu...@gmail.com> wrote: > Hello, > > How VMs receive CPU shares when cpu over provisioning factor is increased > and CPU cap is disabled for them? > > Thanks >