Hitachi, Ltd.

Sakoh Ishikawa

Kenichi Kurosawa

Noboru Masuda

Michio Morioka

Tetsuaki Nakamikawa

Bunichi Fujita

Seiichi Kawashima

Yuzuru Fujita

To provide a large scale multiprocessor system capable of executing an area limited cache coherency control implementing a high speed operation while substantially reducing the amount of processor-to-processor communications there is provided a translation lookaside buffer which retains cache coherency attribute information defining a limitable cache coherent area to maintain data consistency among caches, and a processor memory interface unit includes a cache coherency control which identifies whether cache coherency is required only within a particular cluster of processors or is required for every one of the cache memories in every one of the clusters throughout the system, on the basis of the contents of the cache coherency attribute information. Further, in another version of large scale multiprocessor system, each cluster may be provided with an export directory which registers an identifier of data whose copy is cached in cache memories in other clusters. Thereby, latency in cache coherency procedures can be reduced greatly, since a cache coherent area can be limited in dependence on various characteristics of data. Further, it is also possible to greatly reduce inter-cluster communication quantities, since it is no longer necessary to broadcast to all processors in the system upon every occasion of a memory read/write.

Multiprocessor system having controller for controlling the number of processors for which cache coherency must be guaranteed

The invention relates to method and apparatus for adjusting a clock signal which is supplied to an electronic apparatus. After the turn-on of a power source of the electronic apparatus, it is detected that a temperature of at least a part of devices in the electronic apparatus substantially reaches a saturation state. When the temperature of the device reaches the saturation state, a phase adjustment of the clock signal of the electronic apparatus is executed. After completion of the phase adjustment of the clock signal, its adjusting state is fixed.

Method and apparatus for adjusting clock signal of electronic apparatus

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Hadano, Japan

Sakoh Ishikawa