Resolving processor and system bus address collision in a high-level cache

摘要

A L2 cache for resolving collisions between processor request originating from a processor and system request originating from a computing unit attached to the system bus is provided. First, the L2 cache snoops a system request to access a shared resource. This shared resource is often an area of main memory contained in the L2 cache. Next, the L2 cache receives a processor request to access the shared resource also. The L2 cache will delay sending an acknowledge signal to the processor. The L2 cache then makes a determination as to whether the address and system request type must be sent to the processor. If data associated with the system request would alter a line in a L1 cache associated with the processor, a retry signal is sent to the processor. If the system request would not alter a line in the L1 cache, the L2 cache will wait until the system request finishes accessing the shared resource to process the processor request, thereby avoiding the sending of a retry signal to the processor.