Fractal Consistency: Architecting the Memory System to Facilitate Verification

One of the most challenging problems in developing a multicore processor is verifying that the design is correct, and one of the most difficult aspects of pre-silicon verification is verifying that the memory system obeys the architecture's specified memory consistency model. To simplify the process of pre-silicon design verification, we propose a system model called the Fractally Consistent Model (FCM). We prove that systems that adhere to the FCM can be verified to obey the memory consistency model in three simple, scalable steps. The procedure for verifying FCM systems contrasts sharply with the difficult, non-scalable procedure required to verify non-FCM systems. We show that FCM systems do not necessarily sacrifice performance, compared to non-FCM systems, despite being simpler to verify.