Browse Prior Art Database

Universal Computer Tracing Facility with Deep Storage Configured Through a User Programmable Interface

IP.com Disclosure Number: IPCOM000111178D
Original Publication Date: 1994-Feb-01
Included in the Prior Art Database: 2005-Mar-26
Document File: 2 page(s) / 104K

Publishing Venue

IBM

Related People

Morris, J: AUTHOR [+2]

Abstract

Described is a universal computer tracing facility with gigabyte storage that can be easily adapted to a computer system through a user programmable interface.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 51% of the total text.

Universal Computer Tracing Facility with Deep Storage Configured
Through a User Programmable Interface

      Described is a universal computer tracing facility with
gigabyte storage that can be easily adapted to a computer system
through a user programmable interface.

      As computer systems become more complex, it becomes necessary
to to collect traces of existing machines in order to better
understand the interaction between various components in the system
and to provide trace data for various design methodologies such as
trace driven model simulation.  Typically, two methods are utilized
to collect such traces.  In the first method, a logic analyzer is
used to monitor a set of signals in a computer and then store trace
events to the analyzer memory.  Setup time for taking the trace is
minimal due to the flexibility provided by the logic analyzer.
However, due to the cost, the amount of analyzer trace memory is
typically no more than 128K.  Thus, only very short traces can stored
with this approach.  The second method substitutes custom hardware
and a large fast memory in place of the logic analyzer thereby
increasing the size of the trace substantially.  However, the
flexibility inherent in the first approach is lost, and the time
required to design custom hardware delays the availability of trace
data for use by designers.

      The following design is disclosed for a universal computer
tracing facility with deep storage that is easily adaptable to many
computer systems through a user programmable interface.   The design,
as seen in figure 1 is composed of the Universal Trace Capture (UTC)
card, the Real-Time Tracing System (RTS) and any logic analyzer with
an external output trigger signal.

      The UTC card is a generic trace filtering card that interfaces
to any computer system through a set of probes.  The card collects
samples of the computer system being traced at set intervals and
stores them in a FIFO buffer contained on the card where they are
either selected as valid trace entries or discarded.  The validation
is determined by the state of an external trigger signal supplied by
the logic analyzer.  It is important to note that due to signal
processing within the logic analyzer, the external trigger signal
lags the arrival of a sample to the FIFO by some constant delay.  To
accomplish the sample validation process, the UTC card initially
writes a user defined number of samples to the FIFO that results in
time delay directly correlating to the time lag inherent in the
external trigger signal supplied the logic analyzer.  After the
initial set of samples have been written in, samples are continuously
read from the FIFO at a rate equal to that of the sample collection
rate.  The net effect is that the number of...