Browse Prior Art Database

Fast and Automatic Identification of Performance Outliners in Trace Data

IP.com Disclosure Number: IPCOM000114929D
Original Publication Date: 1995-Feb-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 2 page(s) / 92K

Publishing Venue

IBM

Related People

Lehr, TF: AUTHOR [+2]

Abstract

"Tracing" a software or hardware system is the recording of the chronology of events or states which the system executed. Trace chronologies are used in performance analysis and debugging. When tracing time-stamps the events, the chronology can be organized visually as a time-line marked with various icons, colors and shapes to represent the events contained in that chronology.

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Fast and Automatic Identification of Performance Outliners in Trace
Data

      "Tracing" a software or hardware system is the recording of the
chronology of events or states which the system executed.  Trace
chronologies are used in performance analysis and debugging.  When
tracing time-stamps the events, the chronology can be organized
visually as a time-line marked with various icons, colors and shapes
to represent the events contained in that chronology.

      In trace time-lines, events are often paired, forming
event-pairs, or "occurrences," with start- and end-times.  Examples
of events which can be paired in this way are the start and end of
processes, functions and system calls.  Thus, occurrences are objects
like processes, functions, system calls or literally any set of
time-stamped paired events.

      Given this, it is clear that occurrences can be nested
(programs can contain functions which contain systems calls ..  et
cetera).  PieScope is a trace visualization tool which depicts
occurrences along several time-lines using bars of color producing
sophisticated chronological bar charts.  A process which is shown on
a 20 second time-line and start at 5 seconds and ends at 10 seconds
would appear as a colored bar parallel to the time-line extending
from one-fourth of the time-line to the half-way mark.  If the
process had made function calls, those calls would be represented at
bars, colored differently from the process bar, contained with the
process bar.

      One of the principal reasons for visualizing a trace is to
render it more understandable by distilling reams of textual
information into visual form.  Trace time-lines permit persons who
are analyzing trace data to examine and understand temporal and
causal relationships among trace occurrences over longer trace
periods than they would by pouring over hundreds or thousands of
pages of textual output.  PieScope has visualized traces which would
require over 7500 pages of textual output.

      While a time-line representation of the traces vividly shows
proper temporal relationships, it often does not suffice to compare
subtle or even large variations in, say, the execution times of many
similar occurrences.  It it difficult in heavily populated traces to
find out lying occurrences.  Outliers are important because they
often point to degenerate or pathological per...