It is disclosed a resource sharing manager, RSM, operative to provide efficient utilization of central processing units, CPUs, within virtual servers, each virtual server having an operating system, OS. The RSM dynamically obtains (902) information about ownership and sharable status of said CPUs, and dynamically determines (904) which CPUs are sharable to which virtual servers. The RSM obtains (906) information about that one or more sharable CPUs are available; and obtains (908) information about that one or more virtual servers require more processing resources. The RSM also assigns (910) a first CPU of said sharable CPUs when available, to a first virtual server of said virtual servers. Information about ownership and sharable status of the first CPU, is hence provided to the OS of the first virtual server. Overhead is reduced by circumventing a hypervisor when sharing CPUs in virtual servers. An increase in efficiency of task execution is provided.