Is it safe to set /proc/sys/kernel/sched_rt_runtime_us to -1?

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  • Is it safe to set /proc/sys/kernel/sched_rt_runtime_us to -1?


In short, setting sched_rt_runtime_us to -1 can be extremely dangerous. A value of -1 means no limit. In other words, a "run-away" real-time task will be permitted to monopolise a CPU which could (potentially) lock up a system. The default value for sched_rt_runtime_us is 950000 or 0.95 seconds. Broadly speaking, this allows 0.05 seconds to be used by other non-real-time tasks (i.e. SCHED_OTHER) - a small window at which to recover a system.

The kernel parameter namely /proc/sys/kernel/sched_rt_runtime_us can be set between -1 and (INT_MAX - 1).

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