$10\mathrm{.}3.$ Least$-$laxity$-$first $($LLF$)$ is a real$-$time scheduling algorithm for periodic tasks. Slack time, or laxity, is the amount of time between when a task would complete if it started now and its next deadline. This is the size of the available scheduling window. Laxity can be expressed as

Laxity deadline time