def guest_resize_mem(self, userid, size):
        """Resize memory of guests.

        :param userid: (str) the userid of the guest to be resized
        :param size: (str) The memory size that the guest should have
               defined in user directory after resize.
               The value should be specified by 1-4 bits of number suffixed by
               either M (Megabytes) or G (Gigabytes). And the number should be
               an integer.

        """
        action = "resize guest '%s' to have '%s' memory" % (userid, size)
        LOG.info("Begin to %s" % action)
        with zvmutils.log_and_reraise_sdkbase_error(action):
            self._vmops.resize_memory(userid, size)
        LOG.info("%s successfully." % action)
Resize memory of guests.

        :param userid: (str) the userid of the guest to be resized
        :param size: (str) The memory size that the guest should have
               defined in user directory after resize.
               The value should be specified by 1-4 bits of number suffixed by
               either M (Megabytes) or G (Gigabytes). And the number should be
               an integer.