In one embodiment, a method for controlling reads in a computer input/output (I/O) interconnect is provided. A read request is received over the computer I/O interconnect from a first device, the request requesting data of a first size. Then it is determined whether fulfilling the read request would cause the total size of a completion queue to exceed a first predefined threshold. If fulfilling the read request would cause the total size of the completion queue to exceed the first predefined threshold, then the read request is temporarily restricted from being forwarded upstream.