List-id: Discussion of API issues surrounding Xen <xen-api.lists.xensource.com>
Hi,
Both the functions set the value of the VCPUs/at_startup but the
changes made by the set_VCPUs_at_startup will be visible only after the
VM is rebooted next time, but using set_VCPUs_number_live you can
change the Boot Number of VCPUs of VM while it is running without
restarting the VM.