Power-Aware Prefetch in Mobile Environments

Prefetching has been widely used to improve system per-formance in mobile environments. Since prefetching also consumes system resources such as bandwidth and power, it is important to consider the system overhead when de-signing a prefetching scheme. This paper proposes a cache-miss-initiated prefetch (CMIP) scheme to ad-dress this issue. The CMIP scheme relies on two prefetch sets: the always-prefetch set and the miss-prefetch set. The always-prefetch set consists of data that should al-ways be prefetched if possible. The miss-prefetch set con-sists of data that are closely related to the cache-missed data item. When a cache miss happens, instead of send-ing an uplink request to ask for the cache-missed data item only, the client also requests for the data items which are within the miss-prefetch set. This reduces not only fu-ture cache misses but also the number of uplink re-quests. Note that the client can ask for several data items in one uplink request with little additional cost. We pro-pose novel algorithms to mine the association rules and use them to construct the two prefetch sets. Simulation re-sults show that our CMIP scheme can greatly improve the system performance in terms of improved cache hit ra-tio, reduced uplink requests, and negligible additional traffic. 1