Building Self-Contained Profiles With Gmpf960 - Intel i960 User Manual

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i960 Processor Compiler User's Guide

Building Self-contained Profiles with gmpf960

A "raw" profile contains program counters, which count how many times
various statements in the source program have been executed.
Information in the PDB is needed to correlate these program counters with
the source program.
A raw profile (that is, a profile simply collected as described previously)
has a very short useful life. When changes are made in your source code,
any raw profiles previously obtained for that program are no longer
accepted by the global decision making and optimization step.
A "self-contained" profile captures the program structure from the PDB
and associates it with the program counters from the raw profile. When
changes are subsequently made to the source program, the global decision
making step interpolates or "stretches" the counters in the self-contained
profile to fit the changed program.
A self-contained profile can be continually used to optimize the program it
was collected for, even after days, weeks, or perhaps months worth of
changes to the program. This frees you from having to collect a new
profile every time the program changes, while still allowing profile-
directed optimizations. Depending upon the nature and quantity of
changes to the program, the accuracy of the profile gradually degrades
over time as more interpolation is done.
A self-contained profile must be generated from a raw profile before the
program that generated the raw profile is relinked. You should always
create a self-contained profile immediately after the raw profile is
collected.
To create a self-contained profile, use the gmpf960 profile merger tool.
gmpf960 is invoked with the raw profile as an input file, as shown in this
example:
gmpf960 -Z mypdb -spf pfile2.spf pfile1.pf
This command creates a self-contained profile from the raw
pfile2.spf
profile . The raw profile was created by executing
pfile1.pf pfile1.pf
the instrumented program that was linked using as the program
mypdb
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