Changeset 11299:483fab98c031
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ruby: Add occupancy stats to MessageBuffers

The most important statistic for measuring memory hierarchy performance is
throughput, which is affected by independent variables, buffer sizing and
communication latency. It is difficult/impossible to debug performance issues
through series buffers without knowing which are the bottlenecks. For finite
buffers, this patch adds statistics for the average number of messages in the
buffer, the occupancy of the buffer slots, and number of message stalls.

NOTE: The message count stat could be used as an alternative way to count

total buffered messages RE: http://reviews.gem5.org/r/3283/. Input on how to

tighten things up is welcome.