Fujitsu Corporation

Hideki Sakata

Tsutomu Tanaka

Hiroyuki Kojima

Masaki Ukai

Akitoshi Ino

Takao Kato

Haruhiko Ueno

Atsuhiro Suga

Tatsumi Nakada

Tomoyuki Okawa

Yoshihiro Kusano

Takeshi Mishina

Akira Nodomi

Junlu Chen

Eiki Ito

A processing device includes multiple processing units and multiple memory devices respectively assigned to the multiple processing units. Each of the multiple processing units includes a cache memory configured to retain data stored in the memory device assigned to itself, and fetched data taken out from the memory device of the processing unit other than itself. When an access request for the fetched data is received from a source processing unit from which the fetched data has been taken out, the cache memory determines occurrence of a crossing in which the access request is received after the cache memory issues write back information instructing to write back the fetched data to the memory device assigned to the source processing unit. If the crossing has occurred, crossing information indicating that the crossing has occurred is output as a response to the access request.

System and method for maintaining cache coherency

An arithmetic processing apparatus includes, a plurality of core memory groups, each of core memory groups including a plurality of arithmetic processing circuits, cache memory circuitry, shared by the plurality of arithmetic processing circuits, including a cache memory, a cache tag that stores a state of the cache memory, a tag directory that stores data possession information by a cache memory in another core memory group, and a memory access control circuit that receives a first memory access request from the cache memory circuitry and controls access to a memory other than a cache memory included in the cache memory circuitry, and a cache memory control circuit that receives a second memory access request from the arithmetic processing circuits and a third memory access request from the another core memory group and controls access to the cache memory.

Arithmetic processing apparatus and control method for arithmetic processing apparatus

A second-level cache device stores part of registration information of data for a first-level cache device in a second-level cache-tag unit in association with registration information in a second-level-cache data unit, and stores the registration information of data for the first-level cache device in a first-level cache-tag copying unit. A coherency maintaining processor maintains coherency between the first-level cache device and the second-level cache device based on the information stored in the second-level cache-tag unit and the first-level cache-tag copying unit.

Coherency maintaining device and coherency maintaining method

A cache-memory control apparatus controls a level-1 (L1) cache and a level-2 (L2) cache having a cache line divided into a plurality of sub-lines for storing data from the L1 cache. The cache-memory control apparatus includes a control-flag adding unit, an L1 cache control unit, and an L2 cache control unit. The control-flag adding unit provides an SP flag to each of the sub-lines. The L1-cache control unit acquires an access virtual address, and, when there is no data at the access virtual address, outputs an L2 cache-access address to the L2-cache control unit. The L2-cache control unit switches the SP flag based on a virtual page number in an L1 index and a physical page number in an L2 index. Based on the SP flag, corresponding one of the sub-lines is written back to the L1 cache.

Cache-memory control apparatus, cache-memory control method and computer product

A cache control method controls data sharing conditions in a processor system having multi-level caches that are in an inclusion relationship. The cache control method indexes an upper level cache by a real address and indexes a lower level cache by a virtual address, and prevents a real address that is referred by a plurality of different virtual addresses from being registered a plurality of times within the same cache. A plurality of virtual addresses are registrable within the upper level cache, so as to relax the data sharing conditions.

Cache control method and processor system

A data processing apparatus temporarily stores data to a cache write buffer and then stores the data in a cache storing device. The cache storage device performs a data storage operation with precedence over another operation even if a store instruction contends with a read instruction for accessing the cache storing device. A storage request low signal, sent from a cache write buffer controlling device to a cache controlling device, allows a read request to have precedence over a store instruction even when there is data stored in the cache write buffer waiting to be transferred to the cache storing device in response to the store instruction. However, when the read instruction contends with the store instruction and a state transition signal, such as an instruction cancellation signal generated from an instruction controlling device, is detected, the cache write buffer controlling device changes the output signal to a storage request high signal that causes the storage operation to have precedence over the read operation.

Data processing apparatus with a cache controlling device

A dynamic address translation processing apparatus in a data processing system having a main memory for storing an address conversion table, and a central processing unit for converting a virtual address to a real address by referring the address conversion table. The central processing unit includes a first register for holding the virtual address, a second register for holding a table entry of the address conversion table corresponding to the virtual address held in the first register and, having an update bit indicative that a page in memory has been written to a third register for holding the real address of the table entry held in the second register, a comparison circuit for comparing the virtual address held in the first register with the other virtual address to be converted to the real address, and an update unit for updating the update bit in the table entry held in the second register. When the virtual address coincides with the other virtual address in the comparison circuit, the table entry converted by the update unit is written into an address of the main memory held in the third register.

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Kawasaki, Japan

Hideki Sakata