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Real Time Spectral Performance Monitor

IP.com Disclosure Number: IPCOM000050945D
Original Publication Date: 1982-Dec-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Hoevel, LW: AUTHOR [+2]

Abstract

A prior article (J. Voldman and Lee W. Hoevel, "The Software-Cache Connection," IBM Journal of Research and development 25, 877-893 (November 1981), describes the uses of spectral analysis to identify regular (periodic) data misses in software.

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Real Time Spectral Performance Monitor

A prior article (J. Voldman and Lee W. Hoevel, "The Software-Cache Connection," IBM Journal of Research and development 25, 877-893 (November 1981), describes the uses of spectral analysis to identify regular (periodic) data misses in software.

The purpose of this article is to describe a way to use the same techniques, without the need of an instruction trace, like a Simmon trace, or of a cache emulator trace.

The basis of the technique is to apply spectral analysis to a binary signal, where "ones" represent misses to the cache, while "zeros" are hits to the cache, and where the time is represented by a reference counter (successive references to memory, i.e., first reference, second reference, etc.).

The invention then is as follows: The SCU (Storage Control Unit) of a given CPU will be modified in such a way (which depends on the model) that it provides a signal of equally spaced pulses for successive references to main memory: one pulse per reference.

When there is a miss to the cache, which is an event that the SCU always knows about, a higher pulse replaces the normal pulse.

This signal is analyzed using an on-line spectraI analyzer. If a pattern of spikes happens sufficiently often, then a command is issued so that the last 16K pulses and the last 16K memory addresses for the 16K references are written in a high speed buffer.

This will certainly slow the machine down, but it will be for a very short amount of time.

Th...