schedule_timeout(9)

💤 schedule_timeout(9) — the "just nap for a bit, bestie" kernel function ✨

okay so this is a page from the Kernel API Manual, and it's about schedule_timeout, which is basically the kernel's way of saying "girl, go to sleep for a minute." 🎀

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🌸 NAME 🌸

schedule_timeout — sleep until timeout 💤

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✨ SYNOPSIS ✨

signed long schedule_timeout (signed long timeout );

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🧚 ARGUMENTS 🧚

• timeout — the timeout value, measured in jiffies. (ya, jiffies. iconic unit, no notes 🫶)

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👑 DESCRIPTION 👑

So the whole vibe here: this makes the current task sleep until timeout jiffies have elapsed. That's it. That's the function. But — and this is the part that's giving ✨main character energy✨ — what actually happens depends on the current task state (peep the set_current_state description too, bestie, they're linked):

• TASK_RUNNING — the scheduler gets called, but the task does not sleep at all. Zero nap. Not even a lil closing of the eyes 😭 And why? Because sched_submit_work does literally nothing for tasks in TASK_RUNNING state. nothing. nada. it's giving unbothered.
• TASK_UNINTERRUPTIBLE — at least timeout jiffies are guaranteed to pass before the routine returns, unless the current task gets explicitly woken up (like, by wake_up_process). So it's a proper deep sleep, no interruptions, no "mom's calling" energy. 💅
• TASK_INTERRUPTIBLE — this one's the light sleeper 🦋 the routine may return early if a signal is delivered to the current task, or if the current task is explicitly woken up. so like, you can be woken. it's fine. it's flexible.

And the glow-up guaranteed at the end: the current task state is guaranteed to be TASK_RUNNING when this routine returns. always. periodt. ⭐

Also, if you specify a timeout value of MAX_SCHEDULE_TIMEOUT, it'll schedule the CPU away without a bound on the timeout — like, no clock, no limit, just vibes 🔥 In that case the return value will be MAX_SCHEDULE_TIMEOUT.

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💖 RETURN 💖

• 0 when the timer has expired — slay, nap complete ✅
• otherwise the remaining time in jiffies gets returned 🕐

And in all cases, the return value is guaranteed to be non-negative. no negativity allowed here, we don't do that 🙈

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🌈 SEE ALSO 🌈

Kernel file ./kernel/time/sleep_timeout.c — go read it, it's cute

• schedule_timeout_interruptible(9)
• schedule_timeout_killable(9)
• schedule_timeout_uninterruptible(9)
• schedule_timeout_idle(9)
• schedule_hrtimeout_range_clock(9)
• schedule_hrtimeout_range(9)
• schedule_hrtimeout(9)
• msleep(9)
• msleep_interruptible(9)
• usleep_range_state(9)

the whole sleep-timeout friend group fr fr 🫶

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✿ and that's the whole page, bestie ✿ this one's chillin' under ./kernel/time, October 2026 edition — go take a nap, you've earned it 💜💤