Abstract: A method and an apparatus to prevent over subscription and thrashing of translation lookaside buffer (TLB) entries in I/O virtualization hardware have been presented. In one embodiment, the method includes performing address translation in a direct memory access (DMA) remap engine within an input/output (I/O) hub in response to I/O requests from a root port using a guest physical address (GPA) queue to temporarily hold address translations requests to service the I/O requests and a TLB. The method may further include managing allocation of entries in the TLB to the address translation requests using an allocation window to avoid over-subscription of the entries and managing de-allocation of the entries using a de-allocation window to avoid thrashing of the entries. Other embodiments have been claimed and described.