Data prefetch method and microprocessor

Abstract

Provided is a prefetch unit, a data prefetch method and a microprocessor. The prefetch unit is used for receiving a plurality of access requirements of multiple addresses for a memory block, and each access requirement is corresponding to one of the addresses in the memory block, and the addresses of the access requirements increase or reduce in a manner of non-monotonicity along with a time function. When receiving the access requirement, the prefetch unit will maintain a largest address and a smallest address in the storage device, a count value of change from the largest address to the smallest address, and a historic record of a fast-fetching line that is stored recently in the memory block. The historic record is related to the required address of the fast-fetching line. The prefetch unit determines a storage direction based on the count value, determines an access state based on the historic record, and prefetches the fast-fetching line which is not indicated as an accessed line to the memory block based on the access state along the accessing direction.

Description

[0001] This application is a divisional application of the application with the title of "prefetch unit, data prefetch method, and microprocessor" with the application date of March 29, 2011 and the application number of 201110077108.7. Technical field [0002] The present invention relates to a cache memory of a general microprocessor, and particularly relates to a cache memory of prefetching data to the microprocessor. Background technique [0003] In recent computer systems, when a cache miss occurs, the time required for the microprocessor to access the system memory will be one or two orders of magnitude longer than that for the microprocessor to access the cache. . Therefore, in order to improve the cache hit rate, the microprocessor integrates prefetching technology to test recent data access patterns and try to predict which data is the next one in the program. The object of access, and the benefits of prefetching are well-known categories. [0004] However, the applicant ...

AI Technical Summary

Problems solved by technology

The first reason is that the program accesses memory according to its structure, whether it is caused by algorithm characteristics or poor programming.

The second reason is that the pipelines and queues of out-of-order execution microprocessor cores often perform memory accesses differently from the program order in which they are generated when they are executed under normal functions.

[0006] Therefore, a data prefetching unit (device) is required to be able to effectively perform data prefetch for the program, and it must take into account that there is no obvious trend ( no clear trend), but there is a clear trend when censored with a larger sample size

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