Computer system maintaining data consistency between the cache and the main memory.

摘要

To effectively execute the cache consistency operations that is executed when an I/O device accesses the main memory. A computer system comprises a processor (1), a cache memory (2) of this processor, a main memory (4), an I/O device (6) directly accessible to this main memory, an I/O controller (7), and the like. It is made so that the I/O controller can execute processing to retain data consistency between the cache memory and the main memory during access to the main memory by the I/O device. The I/O controller has an address buffer (9) that retains the cache line address of the previous access by the I/O device and it is made so that the consistency maintenance operation is not executed in cases other than the first access when accesses to the main memory by the I/O device are made continuously in the same data block. <IMAGE>