Electrical computers and digital processing systems: processing – Processing control – Processing control for data transfer
Reexamination Certificate
1998-03-31
2002-08-06
Ellis, Richard L. (Department: 2183)
Electrical computers and digital processing systems: processing
Processing control
Processing control for data transfer
C712S241000, C711S137000, C711S213000
Reexamination Certificate
active
06430680
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
The present invention relates in general to data processing and, in particular, to a processor and method for fetching data from memory. Still more particularly, the present invention relates to a processor and method for prefetching data from memory based upon a detected stride.
2. Description of the Related Art
As processor clock frequencies have continued to increase, thereby permitting increased instruction throughput, memory latency has become a principal impediment to improved processor performance. Although instructions are commonly speculatively fetched from memory in order to ameliorate the effects of instruction access latency, in a conventional processor data is fetched from memory only after a load instruction has been executed to determine the address of the data to be fetched (i.e., only demand fetching is used).
The present invention includes a recognition that in order to reduce data access latency, it is desirable to intelligently prefetch data from memory.
SUMMARY OF THE INVENTION
It is therefore one object of the present invention to provide an improved method and system for data processing.
It is another object of the present invention to provide an improved processor and method for fetching data from memory.
It is yet another object of the present invention to provide a processor and method for prefetching data from memory based upon a detected stride.
The foregoing objects are achieved as is now described. According to the method of the present invention, a first difference between a first load address and a second load address is calculated. In addition, a determination is made whether a second difference between a third load address and the second load address is equal to the first difference. In response to a determination that the first difference and the second difference are equal, a fourth load address, which is generated by adding the third address and the second difference, is transmitted to the memory as a memory fetch address. In an embodiment of the data processing system including a processor having an associated cache, the fourth load address is transmitted to the memory only if the fourth load address is not resident in the cache or the target of an outstanding memory fetch request. The above as well as additional objects, features, and advantages of the present invention will become apparent in the following detailed written description.
REFERENCES:
patent: 4918587 (1990-04-01), Pechter et al.
patent: 5588128 (1996-12-01), Hicok et al.
patent: 5694568 (1997-12-01), Harrison, III et al.
patent: 5802566 (1998-09-01), Hagersten
patent: 5953512 (1999-09-01), Cai et al.
patent: 6138212 (2000-10-01), Chiacchia et al.
Kim, Sunil et al., Stride-directed Prefetching for Secondary Caches, IEEE, 1997, pp. 314-321.*
Fu, John W. C., Stride Directed Prefetching in Scalar Processors, IEEE 1992, pp. 102-110.*
Dahlgren, Fredrik et al., Effectiveness of Hardware-Based Stride and Sequential Prefetching in Shared-Memory Multiprocessors, IEEE 1995, pp. 68-77.
Burky William Elton
Schroter David Andrew
Tung Shih-Hsiung Stephen
Vaden Michael Thomas
Bracewell & Patterson L.L.P.
Carwell Robert M.
Ellis Richard L.
International Business Machines - Corporation
LandOfFree
Processor and method of prefetching data based upon a... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Processor and method of prefetching data based upon a..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Processor and method of prefetching data based upon a... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2943870