AUTHORS:
Daniel Becker, Felix Wolf und Rolf Rabenseifner:

TITLE: 
Time Stamp Synchronization for Event Traces of Large-Scale Message Passing Applications. 
 
ABSTRACT: 
Identifying wait states in event traces of message-passing
applications requires measuring temporal displacements between
concurrent events. In the absence of synchronized hardware clocks, linear
interpolation techniques can already account for differences in offset and
drift, assuming that the drift of an individual processor is not time dependant.
However, inaccuracies and drifts varying in time can still cause
violations of the logical event ordering. The controlled logical clock algorithm
accounts for such violations in point-to-point communication
by shifting message events in time as much as needed while trying to
preserve the length of intervals between local events. In this talk, I
describe how the controlled logical clock is extended to collective communication
to enable a more complete correction of realistic message-passing
traces. In addition, I present a parallel version of the algorithm that
is intended to scale to thousands of application processes and outline its
implementation within the framework of the scalasca toolkit.

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The talk was presented at
Dagstuhl Seminar 07341
Schloß Dagstuhl, Wadern, Germany, Aug. 19-24, 2007.