According to the present invention, methods and apparatus are provided for
increasing the efficiency of data access in a multiple processor,
multiple cluster system. A home cluster of processors receives a cache
access request from a request cluster. The home cluster includes
mechanisms for instructing probed remote clusters to respond to the
request cluster instead of to the home cluster. The home cluster can also
include mechanisms for reducing the number of probes sent to remote
clusters. Techniques are also included for providing the requesting
cluster with information to determine the number of responses to be
transmitted to the requesting cluster as a result of the reduction in the
number of probes sent at the home cluster.