Remote node accessing local memory by using distributed shared memory

#The present invention relates to a distributed shared memory (DSM) architecture in a multi-processor system, and more particular to a distributed shared memory architecture in which a remote node accesses a local memory by using the distributed shared memory system. The present invention also relates to a DSM system utilizing the data access algorithms according to the present invention.

#Due to the increasing advance of science and technology, digitized information processing means plays a more and more important role on our daily lives and business activities. Consequently, the data processing amount is too huge to be operated by using a simple data processing device, such as a computer system with a single processor and a local memory. In order to efficiently deal with a large quantity of data, a processing system involving a distributed shared memory (DSM) is developed for parallel data-processing and rapid data-sharing purpose for a remote node to access a local memory.

#Please refer to FIG. 1, which is a schematic block diagram of a multi-processor computer architecture having a distributed shared memory (DSM). For example, a computer system with one or more processors can be considered as a DSM node. As shown in FIG. 1, the computer system is a multiprocessor computer architecture. In general, the computer system with a single processor can be consider as a DSM node, too. Processors 110 and 120 included in the DSM node are electrically connected to a memory control chip 130 via a system bus 160. By way of the memory control chip 130, the access operations between the processors 110, the processor 120 and a local memory 150 is controlled. The memory control chip 130 could be further electrically connected to other devices for basic input/output control and the task of the memory control chip 130 is executed by a north-bridge chip in a computer system.

#The present invention may best be understood through the following description with reference to the accompanying drawings, in which:

#FIG. 1 is a schematic circuit block diagram showing a distributed shared memory (DSM) structure;

#FIG. 2 is a schematic diagram showing various status of a local memory line, including HOME, SHARED, GONE and WASH;

#The present invention will now be described more specifically with reference to the following embodiments. It is noted that the following descriptions of preferred embodiments of this invention are presented herein for purpose of illustration and description only; it is not intended to be exhaustive or to be limited to the precise form disclosed.

#The DSM node as shown in FIG. 1 is used for illustrating an embodiment of the present invention. The status of the local memory line indicated by a memory coherency directory, however, are modified to solve the problems encountered by the prior art. Please refer to FIG. 3 which is a schematic diagram showing various status of a local memory line. In an embodiment of the present invention, the status of a local memory line indicated by a memory coherency directory including HOME-M, HOME-N, SHARED, GONE and WASH, wherein the meanings of the SHARED, GONE and WASH status are similar to the above-mentioned prior art DSM node system, and the meanings of HOME-M and HOME-N are:

#HOME-N: The data from the local memory line is not read by any remote node, and the latest data in a local memory line is stored in the local memory; and