The Linux kernel scheduler is a complicated beast
and a lot of effort goes into improving it during every kernel release
cycle. The 5.4 kernel release includes a few improvements to the existing
SCHED_IDLE scheduling policy that can help users improve the
scheduling latency of their high-priority (interactive) tasks if they use
the SCHED_IDLE policy for the lowest-priority (background)
tasks. Read on for a description of this work contributed by Viresh Kumar.

Source: LWN.net – [$] Fixing SCHED_IDLE