Browse Prior Art Database

Address Stream Capture

IP.com Disclosure Number: IPCOM000086318D
Original Publication Date: 1976-Aug-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 43K

Publishing Venue

IBM

Related People

Spencer, DR: AUTHOR

Abstract

This scheme permits the capture of address streams with a minimum storage requirement. In order to analyze the performance effects of various design alternatives in the memory hierarchy area, it is desirable to be able to capture address streams from a running computer system without affecting the operation of the system being measured. Both real and virtual address streams are required for different studies.

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Address Stream Capture

This scheme permits the capture of address streams with a minimum storage requirement. In order to analyze the performance effects of various design alternatives in the memory hierarchy area, it is desirable to be able to capture address streams from a running computer system without affecting the operation of the system being measured. Both real and virtual address streams are required for different studies.

The measurement box contains two recording media. One medium 10 would record a short record for each address generated by the processor. This short record would contain an encoded cache address, or in the case of a cache miss, the cache address of the location into which the information will be placed (store- in-buffer assumed). The second medium 12 would record full address records only on cache misses.

After recording the desired period of operation, the virtual address stream can be reconstructed by processing records from both recording media by a suitable program. The program would maintain a mapping of cache location to currently assigned virtual address, reassigning virtual addresses upon cache misses. Short records would be translated into virtual addresses through this mapping. Possible recording formats for both real and virtual addresses are shown.

To capture a real address stream rather than virtual, it is only necessary to probe real address lines rather than virtual on the processor being traced, and to change the program mapping to cache location from virtual to real addresses. A ...