Processes requiring Real-Time Scheduling fail with "sched_setscheduler: Operation not permitted" error or similar

Solution Verified - Updated -


  • Services trying to acquire real-time scheduling fail to start, strace on the service executable shows a EPERM (Operation not permitted) error when calling the sched_setscheduler syscall with SCHED_RR parameter:

    # strace <program> 2>&1 >/dev/null | grep sched_setscheduler
    sched_setscheduler(0, SCHED_RR, { 99 }) = -1 EPERM (Operation not permitted)
  • Services acquiring real-time scheduling start normally at boot, but fail to be restarted, and usually show the error message shown above


  • Red Hat Enterprise Linux (RHEL) 7
    • systemd

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