Initial Results of the Performance Implications of Thread Migration on a Chip Multi-Core
Y. Sazeides*, P. Michaud+, L. He*, D. Fetis+, P. Charalambous*, C. Ioannou*, A. Seznec+ 
*University of Cyprus, Nicosia, Cyprus +Irisa-Inria, Rennes, France

Thread-migration is an emerging method for research that leverages multi-cores to alleviate 
the temperature problem by distributing thread activity and power consumption more uniformly 
over the entire chip. Our research aims to establish how effective is thread-migration at 
solving the power density problem for a thermally constrained multi-core and determine how 
to best implement thread migration to address the temperature problem.

In this talk we present initial results that quantify the performance implications of thread
migration on a four core system when the workload consists of one to four threads from 
SPEC CPU 2000 benchmarks. Overall, the results reveal that a simplistic implementation 
of activity migration can have significant performance overhead. Consequently, if thread 
migration is to be successful, novel mechanisms are needed to minimize the cold effects 
and flushing overhead of large private caches. The data also suggest a need to reduce the
cold predictor effects for the case when a core is visited by one or more threads before a
same thread revisits it.