Fujitsu Corporation

Yuka Hosokawa

Takashi Yamamoto

Toshikazu Ueki

Makoto Hataida

Takaharu Ishizuka

Daisuke Itou

Takeshi Owaki

Takao Matsui

Atsushi Morosawa

Hiroshi Nakayama

Seishi Okada

Kenta Sato

Masayoshi Matsumura

Atsushi Morozawa

A memory control apparatus includes a randomizer configured to: randomize write data output from an arithmetic processing apparatus, and output the randomized write data to a memory; a derandomizer configured to: derandomize data read from the memory, and generate derandomized read data when a flag included in the data read from the memory indicates the randomized write data; and a selector configured to: select the derandomized read data and output the selected derandomized read data to the arithmetic processing apparatus when the flag indicates the randomized write data, and select the data read from the memory and output the selected read data to the arithmetic processing apparatus when the flag indicates deleted data.

Memory control apparatus, information processing apparatus, and memory control method

A data transfer device includes a data transmitting circuit includes an error detection code generating unit generating an error detection code for detecting an error in the data, and a transmission unit transmitting the data and the error detection code together with retransmit enable information representing that corresponding data transmitted before the former data or transmitted next can be retransmitted, the data receiving circuit includes a reception unit receiving the transmitted data, the transmitted error detection code and the transmitted retransmit enable information, an error detection unit detecting the error in the received data based on the error detection code, an error data retaining unit retaining the data in which an error is detected when the reception unit receives the retransmit enable information, and an error data comparing unit that comparing the error detected data retained in the error data retaining unit with corresponding data that is retransmitted.

Data transfer device and control method of data transfer device

To prevent a decrease in performance of controlling a snoop tag. A queue is stored with REPLACE target WAY information and an index as an entry associated with a REPLACE request received from a processor, the index stored in the queue is compared with an index of a subsequent READ request, and, as a result of the comparison, a process based on the index-coincident READ request is executed with respect to the snoop tag corresponding to a content of a cache memory of the processor. Further, the REPLACE target WAY information of the READ request is replaced with the WAY information in the index-coincident entry within the queue.

Control device for snoop tag

A northbridge, when detecting a synchronization break of a redundant CPU, stops the operation of an abnormal CPU bus where an error has occurred and the firmware in a firmware hub instructs the northbridge to inhibit an external instruction. In addition, the firmware saves the inside information of a normal CPU connected to a normal CPU bus and cache data on a memory and the northbridge issues reset to all CPUs in the home system board. The firmware then restores the inside information of the CPU saved on the memory to all CPUs and instructs the northbridge to cancel the inhibition of the external instruction.

Information processing apparatus for inhibiting instructions, saving and restoring internal information in response to abnormality in redundant processor system

A request issued by the CPU is output from the local arbiter by way of the CPU bus and the CPU-issued request queue. The cache replacement request loop-back circuit determines at the loop-back determination circuit whether the outputted request is a cache replacement request or not. A request other than a cache replacement request is output onto the local bus. A cache replacement request is output to the selector and sent to the request handling section when there is no valid request on the global bus.

Multiprocessor system, system board, and cache replacement request handling method

An information processing device having two processing units capable of operating in synchronization with each other, includes: a common unit capable of outputting an identical signal to the two processing units; detection units that are respectively provided for the processing units and each detects errors occurred in corresponding processing unit respectively; a comparison unit that compares outputs from the two processing units; and a control unit that controls signals from the processing units to the common unit, based on a detection result of the detection units and a comparison result of the comparison unit, and determines, if errors of an identical type are simultaneously detected by the detection units, that the errors are due to an error of the common unit.

Information processing device and error processing method

A control device managing a plurality of nodes transmitting and receiving data containing an error correcting code, comprises means accepting, when any one of the nodes detects an uncorrectable error from the data containing the error correcting code, a signal transmitted by the node detecting the error, means judging from a record of the detection of a first node, when accepting the signal from a second node receiving data transmitted by the first node, whether or not the first node has detected the uncorrectable error from the data transmitted to the second node, and means stopping, when the first node has detected the uncorrectable error from the data transmitted to the second node, a process attributed to the acceptance of the signal from the second node.

Node device, control device, control method and control program

In a system controller including a CPU-issued request queue having a circuit that processes plural requests having identical addresses not to be inputted to the CPU-issued request queue, a latest request other than a cache replace request is retained by an input-request retaining section. Consequently, even if an address of an issued request for cache replace request matches an address of a request retained by the CPU-issued request queue, the issued request for the cache replace request is not retried but is queued in the CPU-issued request queue when the address of the issued request for the cache replace request does not match the entire address retained by the input-request retaining section.

System controller, identical-address-request-queuing preventing method, and information processing apparatus having identical-address-request-queuing preventing function

In an information processing system loaded with a CPU having cache and a system controller having a copy of a tag of the cache (snoop tag), and the CPU not issuing replacement information about the cache tag, the number of WAYs of the snoop tags in the system controller is larger than the number of WAYs of the cache tags in the CPU to reduce a cache miss rate and suppress the degradation of performance by suppressing excess replacement of the cache tags in the CPU.

Information processing system, information processing board, and method of updating cache tag and snoop tag

In a multiprocessor system, a system controller includes snoop tags which are copy information on cache tags retained by respective CPUs. If the same address is registered in S (Shared state) in the cache tag of each of the CPUs connected to the same CPU bus, the address is registered in S (Shared state) in only any one of the snoop tags corresponding to the CPUs in which the same address is registered.

System controller, snoop tag modification method and information processing apparatus having snoop tag modification function

A multiprocessor system includes a judging unit judging whether a read command inputted to a global address crossbar is a read command to a memory on an own system board, an executing unit speculatively executing, when the judging unit judges that the read command is a read command to the memory on the own system board, the read command before global access based on an address notified from the global address crossbar, a setting unit setting for queuing data read from the memory in a data queue provided on a CPU without queuing the data in a data queue provided on the memory, and an instructing unit instructing, based on notification from the global address crossbar, the data queue provided on the CPU to discard the data or transmit the data to the CPU.

Multiprocessor system

In the present invention, in order that a busy judgment of a register can be made without fail and without increasing the number of hardware resources for storing a request into the register provided at the final stage of a pipeline register in a stage in which the request is retained halfway in the pipeline register in a pipeline processor, a first counter for counting the number of valid requests in the registers between a judgment section interposed in the pipeline register and for judging whether the request is a valid request and a request queue and a busy judgment section for judging whether the request queue is in a busy state based on the number of valid requests counted by the first counter are provided and a judgment is made by the judgment section based on the result of the busy state judgment by the busy judgment section.

Counter counts valid requests based on a judgment in a system having a plurality of pipeline processors

A dual storage apparatus is provided that comprises a first and a second memories for respectively retaining a set of identical data and a selector for selecting either of the two (2) sets of the data respectively read from the first and the second memory based on a read control signal inputted into the selector, having a request management unit for, when the read control signal has been inputted, attaching an identifier for identifying the read control signal to the inputted read control signal and outputting the signal and the identifier; and a plurality of memory control units for each of the first and the second memories. The dual storage apparatus detects a synchronization error by verifying coincidence of the identifier attached by the request management unit and controls the selector such that the data from a system from which no synchronization error has been detected.

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Kawasaki, Japan

Yuka Hosokawa