The present invention, generally speaking, provides a hierarchy of
configuration storage. The highest level of the hierarchy is an active
configuration store; the lowest level is an off-chip configuration store;
in between are one or more levels of configuration stores. Every
configuration is promoted from the lowest off-chip level, through each
level, up to the highest active level. Each ascending level of the
hierarchy has a decreasing latency time required to promote a
configuration to the next higher level of the hierarchy, and a decreasing
amount of available storage. This separation into levels allows the
amount of available storage to be adjusted depending on the inherent
latency of the level's storage mechanism, where a longer latency requires
a larger cache. This in turn allows the total required storage for a
given performance level to be minimized.