Stabilizing execution time of user processes by bottom half scheduling in Linux

The CPU time allocated to user processes is rendered inaccurate by an unexpectedly and frequently occurring interrupt and a bottom half that consumes most interrupt processing time. Additionally, when the time consumed in the kernel mode greatly fluctuates with interrupt processing, the scheduler cannot distribute CPU time to user processes normally. This problem can dramatically distort the stable execution time of user processes. In addition, such time-sensitive applications as multimedia players cannot provide consistent quality. To overcome this stolen-time problem, we propose a bottom half scheduling approach that dynamically restricts the maximum time consumed by bottom halves. In this paper, we implement our proposed scheme in Linux 2.4. In addition, we show that the fluctuation of CPU time allocated to user processes by stolen-time can be shrunk with our proposed scheme by means of experiments using a multimedia application.