HP Caliper User's Guide

A HP Caliper Diagnostic and Warning Messages
This appendix describes some diagnostic and warning messages you might receive.
HP Caliper always attempts to measure everything that you request. When this is not
possible, however, HP Caliper gives you diagnostic or warning messages. You can
usually safely ignore these messages.
Several situations can cause these messages:
• A sampled address is outside the measurement context.
• A function contains specialized assembly code.
• A function cannot be identified.
• A function does not follow the standard language run-time convention.
• HP Caliper has exceeded some internal limit such as available memory.
HP Caliper reports the first problem it encounters. There might be more than one
problem in a given set of circumstances, but only the first is reported.
ERROR #28: Caliper Invalid Measurement Combination
This message means that HP Caliper was not able to program the PMU successfully
because of oversubscribed resources.
The Integrity servers PMU contains four event counters (12 on the Integrity servers
dual-core Itanium 2 and Itanium 9300 quad-core processors). However, not all PMU
events can be counted by all counters. In particular, most events that can occur multiple
times per cycle will be restricted to one of two counters. If you try to measure more
than two such events, HP Caliper reports the error.
In addition, one event counter is used to control the sampling, so the largest number
of events that can be measured is three.
To fix this problem, make multiple runs specifying fewer events in each run.
Instructions Labeled STUB
Some instructions that are executed do not belong to a function. They can belong to
stubs, which in turn call a desired target function. This is common, especially for
shared-bound executables.
When a stub can be correlated to a function, it will be reported as {STUB} ->
function. When the association cannot be made, HP Caliper reports it as *STUB*.
Mispredicted Branches
The branch trace buffer reports a branch as mispredicted when either outcome of the
branch (taken or not taken) or the target of the branch are incorrectly predicted.
So even if a branch is marked with the hint .sptk (statically predicted taken) and
if the branch is always taken, it can be marked as mispredicted if the processor could
not predict the branch target correctly.
ERROR #28: Caliper Invalid Measurement Combination 215