Selective segment initialization: Exploiting NVRAM to reduce device startup latency

Abstract

We propose selective segment initialization (SSI) to exploit NVRAM to reduce the device startup latency. SSI locates a kernel binary image in byte-addressable NVRAM and boots the system using this image, eliminating the need to load it from storage. SSI also eliminates the process of decompressing and relocating the OS kernel image in embedded Linux system. The key technical ingredients of SSI are precisely identifying the kernel segments where contents are updated in the course of booting and selectively reloading only these sections each time the system reboots. The fresh copy of the sections can be maintained in NVRAM, NAND flash, NOR flash, etc. In our experiment, SSI reduced the size of the kernel binary image loaded from storage into memory by 90% and reduced the overall device startup time by 54%. This approach can be used not only for cold boot (with NVRAM) but also for warm boot, in which the contents of DRAM persist across the system restart.