Abstract: A method and apparatus for improving read latency for processor to system memory read transactions is disclosed. One embodiment of a system logic device includes logic that assumes a transfer size of a predetermined length. In this manner, the system logic device can issue a read transaction request to system memory as soon as the read request address is delivered by the processor rather than waiting for the processor to deliver information indicating the transfer length. Once the actual transfer length information is delivered from the processor to the system logic device, the system logic device determines whether any of the data returned by the system memory needs to be purged before returning the requested data to the processor.

Abstract: According to one embodiment, a computer system is disclosed that includes a memory and a memory controller coupled to the memory. The memory controller includes an arbitration unit that may be programmed to operate according to a first arbitration mode or a second arbitration mode. The computer system also includes a first device and a second device coupled to the arbitration unit. According to a further embodiment, the first device is assigned a higher priority classification than the second device for accessing the memory while the arbitration unit is operating according to the first arbitration mode. In addition, the first device and the second device are assigned equal priority classifications for accessing the memory while the arbitration unit is operating according to the second arbitration mode.

Abstract: A computer system is provided. The computer system includes a host processor (HP), a system memory (SM), and an input/output (I/O) master device to perform a read of a continuous stream of data to the SM. The computer system also includes a bridge coupled to the HP, SM, and I/O master device. The bridge reads ahead to the SM when the I/O master device reads a continuous stream of data from the SM. The bridge aborts read ahead accesses to the SM, prior to an access commit point to the SM, responsive to disengagement of the I/O master device.