Measuring Distributed Durations with Stable Errors
António Casimiro, Pedro Martins, Paulo Veríssimo and Luís Rodrigues
Selected sections of this report were published in the proceedings of
the 22nd IEEE Real-Time Systems Symposium (RTSS 2001), London, UK,
December 3-6, 2001.
The round-trip duration measurement technique is fundamental to
solve many problems in asynchronous distributed systems. In
essence, this technique provides the means for reading remote
clocks with a known and bounded error}. Therefore, it is
used as a fundamental building block in several clock
synchronization algorithms. In general, the technique can be used
to implement duration measurement services, such as the one of the
Timely Computing Base model. In this paper we propose a
new technique to measure distributed durations that minimizes the
measurement error and is able to keep this error almost stable. The
new technique can be used to improve the precision of remote clock
reading in certain situations. We provide a protocol that
implements this new technique and we present some evaluation
results. The results clearly show that our solution is indeed
better than existing ones.
Also available extended report (gzip postscript), (pdf) .