Energy-Efficient Data Caching and Prefetching for Mobile Devices Based on Utility Huaping Shen, Mohan Kumar, Sajal K. Das, and Zhijun Wang. P76934408 邱仁傑. Outline. Scalable Asynchronous Cache Consistency Scheme (SACCS) Analytical Model for Utility GD-LU Cache Replacement Algorithm
Each data item in the system is in one of three states: invalidated, certain and uncertain .
A mobile device is either in an awakeor in a sleepstate
In the awake state (i.e., connected with base station (BS)), mobile device receives the IR
In the sleep state
Upon wake up ,mobile devices set all data items in the cache into uncertain state.
An uncertain entry must be refreshed or checked before its usage.
If applications request an item that is in uncertain state
The notations used in the analysis are listed below:
where is victim data set chosen from the uncertain data set and is victim data set chosen from the certain data set.
The energy cost after the (n+1)th request can be expressed in a recursive way as follows:
where C is the set of data items in cache, and uj is the utility value of cached data item j.
GD-LU mechanism : it uses a priority queue of the data items based on their utility values.
Passive prefetching algorithm : due to a priority queue management, the it also has a time complexity of O(logN).
GD-LU replacement algorithm and compare it with