Improving swap I/O performance for android smartphone with eMMC

Abstract

For the last decade, market share of Android smartphone has been gradually increased by the development of smartphone technology. As the number of cores, memory size and storage size are increased, sizes of applications which are executed in smartphones are also increased. However, current Android OS terminates one of the processes by force while the lack of memory situation is happened. This means that user loses the previous state of victim process which is selected to terminate when user excessively executes multiple applications. Because of this problem, user has to repeat the progress to roll back the previous state of victim application. Meanwhile, Using swap area is one of the solutions to prevent the lack of memory situation for the desktop PC or server in general. By making swap partition in the storage, more process can be executed as if machine has more memory space. Previously, swap mechanism is not adapted to the Android smartphones because the application working set size is small because the limited cpu performance. Also, performance gap between memory and disk was too huge to use swap mechanism. But the situation is changed by the occurrence of eMMC which is the newest storage for the smartphone. So we consider the swap mechanism for Android by using eMMC to solve the lack of memory problems of current Android. There are several researches for swap mechanism for smartphone for NAND flash memory as a secondary storage. However, their improvements were proved by simulation, not in real implementation and they assume that OS knows whole information about read/write request for block of NAND flash. But case of eMMC, OS doesn`t know that information because the FTL layer is included in the storage itself.So it is impossible to adopt their policy into current eMMC. It means that there is no appropriate approach for managing swap area for eMMC currently. In this thesis, we propose three swap I/O management techniques for Android smartphone to improve ...