摘要:
A cache memory device in an N-way (N is an integer of 2 or larger) set associative system includes a way detection unit detecting one way exhibiting a specified strength on the basis of a reference history defined as bits representing a win/loss relation between ways and updated so as to indicate one way exhibiting the specified strength, and an error detection unit detecting a bit error in the reference history if the way detection unit does not detect one way exhibiting the specified strength.
摘要:
The present invention relates to a multithread processor. In the multithread processor, when a cache miss occurs on a request related to an instruction in, of a plurality of caches arranged hierarchically, a cache at the lowest place in the hierarchy, with respect to the request suffering the cache miss, a cache control unit notifies an instruction identifier and a thread identifier, which are related to the instruction, to a multithread control unit. When a cache miss occurs on an instruction to be next completed, the multithread control unit makes the switching between threads on the basis of the instruction identifier and thread identifier notified from the cache control unit. This enables effective thread switching, thus enhancing the processing speed.
摘要:
An apparatus for controlling data transfer performed with a computer connected to a data bus, which performs data transfer in one direction, the apparatus includes a data transfer controlling unit that controls the data transfer with the computer by setting a data bandwidth of an input bus to be greater than a data bandwidth of an output bus, where the input bus transfers data to be input to the computer, and the output bus transfers data output by the computer.
摘要:
An apparatus for efficient parallel executing instruction avoiding the usage of cross bypasses, the apparatus including an instruction buffer for storing instructions, of decoders for decoding, in parallel, the instructions which simultaneously issue from the instruction buffer, executing units for executing the instructions decoded in the decoders, and an instruction-issuing controlling means for controlling the issuing of the instructions in such a way that, when the instructions are executed, one of the plural executing units executes instructions more frequently than the rest of the plural executing units. The apparatus is preferably incorporated in an information processor to superscalar or out-of-order instruction execution.
摘要:
A cache memory includes a first-level cache-memory unit that stores data; a second-level cache-memory unit that stores data that is same as the data stored in the first-level cache-memory unit; a storage unit that stores a part of information relating to the first-level cache-memory unit; and a coherence maintaining unit that maintains cache-coherence between the first-level cache-memory unit and the second-level cache-memory unit based on information stored in the storage unit.
摘要:
An apparatus includes a branch instruction prediction unit configured to make branch prediction, and a branch prediction control unit configured to control an instruction fetch control unit, an instruction buffer, an instruction decoder, and the branch instruction prediction unit, wherein when the branch prediction control unit ascertains that the branch prediction by the branch instruction prediction unit is erroneous, the branch prediction control unit outputs to the instruction fetch control unit a signal for suppressing an instruction fetch request already supplied to the memory unit and outputs to the instruction buffer a signal for nullifying the instruction buffer during a period between a point in time at which the ascertainment is made by the branch prediction control unit that the branch prediction by the branch instruction prediction unit is erroneous and a point in time at which the instruction buffer fetches a correct instruction from the memory unit.
摘要:
A branch history information write control device in an instruction execution processing apparatus includes a memory unit storing an instruction string, and a branch prediction unit performing a branch prediction of a branch instruction. A control unit in the device controls the memory unit and the branch prediction unit in such a way that writing of branch history information in the branch prediction unit and control over fetching of the instruction string in the memory unit may not occur simultaneously so that no instruction fetch is held. A bypass unit in the device makes the branch history information of the branch instruction a research target of a branch prediction, where said control unit uses a counter to count several clock cycles (several states) to delay, for a period of several clock cycles (several states), the writing of the branch history information and control, beforehand, the fetching of the instruction string.
摘要:
An error judging circuit includes a first EOR circuit tree that generates a check bit of a correction code by polynomial remainder calculation with respect to a polynomial expression of an original code which is protected from an error with respect to data of m bit block unit by addition in a Galois extension field GF (2m) in SmEC-DmED using Reed-Solomon code, a second EOR circuit tree for generating syndromes from Sn=Y(αn) with respect to code C(x) in which the check bit is added to the original code when a polynomial representation of a code which is to be detected an error and has a possibility that an error is mixed is Y(x), and an error detection circuit unit that detect if there is a one block error, a two block error, or no error based on whether or not an equation of syndromes S12=S0S2 is satisfied.
摘要:
A processing apparatus includes an execution unit which performs computation on two operand inputs each being selectable between read data from a register and an immediate value. The processing apparatus also includes another execution unit which performs computation on two operand inputs, one of which is selectable between read data from a register and an immediate value, and the other of which is an immediate value. A control unit determines, based on a received instruction specifying a computation on two operands, whether each of the two operands specifies read data from a register or an immediate value. Depending on the determination result, the control unit causes one of the execution units to execute the computation specified by the received instruction.
摘要:
A barrier synchronization device for realizing barrier synchronization of at least 2 processor cores belonging to a same synchronization group among a plurality of processor cores is included in a multi-core processor having a plurality of processor cores, and when two or more processor cores in that multi-core processor belong to the same synchronization group, the included barrier synchronization device is used for realizing barrier synchronization.