Prefetch command control method, prefetch command control apparatus and cache memory control apparatus
First Claim
1. A prefetch command control method comprising:
- generating a prefetch command for data with information specifying a utilization time of the data;
scheduling an issuance timing of the prefetch command according to the information specifying the utilization time; and
calculating an issuance cost of the prefetch command based on a period of time for which a prefetched data stays in a cache when the prefetch command is issued, and wherein the issuance timing of the prefetch command is scheduled according to the issuance cost.
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Accused Products
Abstract
A prefetch command control apparatus is provided. A protocol slot generation unit, when receiving from a CPU a prefetch command in which a utilization time of data to be prefetched is specified, generates a protocol slot based on the utilization time and registers it in a schedule list storage unit. When receiving a regular access command, the protocol slot generation unit registers a protocol slot in a regular protocol queue storage unit. A cost evaluation unit evaluates an issuance cost of the prefetch command based on a cache retention time of data to be prefetched and evaluates an issuance cost of the regular access command based on a resource occupation cost. A protocol issuance unit decides which command shall be issued, the prefetch command or regular access command, based on the evaluation result of these issuance costs.
10 Citations
19 Claims
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1. A prefetch command control method comprising:
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generating a prefetch command for data with information specifying a utilization time of the data; scheduling an issuance timing of the prefetch command according to the information specifying the utilization time; and calculating an issuance cost of the prefetch command based on a period of time for which a prefetched data stays in a cache when the prefetch command is issued, and wherein the issuance timing of the prefetch command is scheduled according to the issuance cost. - View Dependent Claims (2, 3, 4, 5)
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6. A prefetch command control apparatus comprising:
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a storage unit which stores a prefetch command for an external resource with information specifying data utilization time added; a cost evaluation unit which evaluates an issuance cost which accrues due to a prefetched data staying in a cache by the specified utilization time when the stored prefetch command is issued; and an issuance unit which adjusts a timing when the stored prefetched command is issued for the external resource according to an evaluation result by the cost evaluation unit. - View Dependent Claims (7, 8, 9, 10, 11, 12)
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13. A cache memory control apparatus comprising:
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a cache memory which caches data obtained from an external resource and provides the cached data to a processor; a scheduler which schedules an access protocol for the external resource received from the processor and sets up the scheduled access protocol in a request queue for the external resource; and an external resource controller which reads the access protocol from the request queue and accesses the external resource to provide data to the cache memory, and wherein the scheduler comprising; a storage unit which stores a prefetch command for an external resource with information specifying data utilization time added; a cost evaluation unit which evaluates an issuance cost which accrues due to a prefetched data staying in a cache by the specified utilization time when the stored prefetch command is issued; and an issuance unit which adjusts a timing when the stored pretetched command is issued for the external resource according to an evaluation result by the cost evaluation unit. - View Dependent Claims (14, 15, 16, 17, 18)
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19. A tangible storage medium storing a computer program executable by a computer, the computer program comprising:
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generating a prefetch command for data with information specifying a utilization time of the data; scheduling an issuance timing of the prefetch command according to the information specifying the utilization time; and calculating an issuance cost of the prefetch command based on a period of time for which a prefetched data stays in a cache when the prefetch command is issued, and wherein the issuance timing of the prefetch command is scheduled according to the issuance cost.
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Specification