sched_setscheduler_nocheck(9)

💅 sched_setscheduler_nocheck

okay so this is a page from the Kernel API Manual — yes that one — and today's main character is sched_setscheduler_nocheck, a little function with a big "i do what i want" energy 🎀

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✨ NAME ✨

sched_setscheduler_nocheck — changes the scheduling policy and/or the RT priority of a thread, and it does it from kernel-space. that's the whole vibe. 🦋

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🌸 SYNOPSIS 🌸

int sched_setscheduler_nocheck (struct task_struct *p , int policy ,
       const struct sched_param *param );

that's the signature bestie, copy it exactly, don't get creative with it 🫶

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🎀 ARGUMENTS 🎀

• p — the task in question. like, this one. the thread we're messing with 💜
• policy — the new policy. as in, the scheduling one. iconic.
• param — a structure containing the new RT priority. it's giving "payload" honestly 😭

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🔥 DESCRIPTION 🔥

so it's just like sched_setscheduler, except — and this is the whole point — it genuinely does not bother checking whether the current context has permission. no vibe check, no permission check, we simply go 💅

ngl, this is needed. for example, it's needed in stop_machine: we create temporary high priority worker threads, but the caller might not actually have that capability. so yeah. we skip the check because the caller might be a little powerless in that moment and we still need it to work. no cap.

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⭐ RETURN ⭐

0 on success. an error code otherwise. that's it, that's the return section 🍓

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👑 SEE ALSO 👑

kernel file ./kernel/sched/syscalls.c — and then the whole friend group:

task_prio(9), idle_cpu(9), idle_task(9), find_process_by_pid(9), sched_setscheduler(9), sys_sched_setscheduler(9), sys_sched_setparam(9), sys_sched_setattr(9), sys_sched_getscheduler(9), sys_sched_getparam(9), sys_sched_getattr(9), sys_sched_setaffinity(9), sys_sched_getaffinity(9), sys_sched_yield(9), yield(9), yield_to(9), sys_sched_get_priority_max(9), sys_sched_get_priority_min(9), sys_sched_rr_get_interval(9)

like. the entire sched extended universe. go read them, iykyk 🌈

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and that's the page!! 💖 sign-off time: this one lives in ./kernel/sched, and it's dated October 2026 — so mark your calendars bestie, the scheduler said see you then 🧚‍♀️✨