US 5,491,811 A · Cache system using mask bits to recorder the sequences for transfers of data through cache to system memory

Abstract

Apparatus and method for improving the rate of transfer of data in the context of a system memory operated in conjunction with a cache. In one form, mask bits in a mask bit register are associated to bytes of cache. The mask bits are changed in state when the corresponding byte in the cache is written. The mask bits are used in a reordered operating sequence to selectively write data from system memory into the cache after a write into cache. Data transfer performance is improved significantly in that the selective writing of data from system memory to cache can be completely eliminated when the mask bits indicate that a whole unit of the cache, typically a cache line, has been written during the data transfer into the cache.

Claims8

Dependent claims

Apparatus for controlling a transfer of data involving a data cache and memory of a computer system, comprising:

a bus connecting the computer system memory and the computer system data cache;
means for transferring data into the computer system data cache;
at least one data unit in the computer system data cache, the at least one data unit comprising a plurality of groups of bits;
a plurality of mask bits, wherein each of the plurality of mask bits is associated with one of the plurality of groups of bits;
means for relating a given state of each of the plurality of mask bits bit to changes in the group of bits associated with that mask bit;
and
means for transferring data from the computer system memory to the computer system data cache in response to the given states of the plurality of mask bits.

4 more elements

Dependencies are inferred from the claim text.

Cache system using mask bits to recorder the sequences for transfers of data through cache to system memory

Life of this patent

Cache system using mask bits to recorder the sequences for transfers of data through cache to system memory

Life of this patent

Abstract

Claims8