Multiprocessor cache analysis using ATUM

A tracing facility called ATUM-2 that allows the capture of large address traces of multiprocessors is described. The method is based on a previous scheme called address tracing using microcode (ATUM) for single processors (see ibid., vol.13, p.119-27, (1986)). In ATUM, the microcode of a machine is modified to record the address of the memory references as a side effect of normal execution. The addresses are recorded in a reserved portion of main memory, and periodically transferred to disk. The ATUM-2 implementation on a VAX 8350 multiprocessor is described and the use of the resulting traces to analyze physical versus virtual addressing of large caches, process-identifier hashing in virtual caches, cache interference between multiple processes, cache interference between multiple CPUs, process affinity, and semaphore usage in writeback caches is reported on