timespec64_to_jiffies(9)

📦 version 7.3.1, in nixpkgs unstable

✨ timespec64_to_jiffies(9) ✨

okay bestie, so this is a page straight out of the Kernel API Manual — yes the real one, the timespec64_to_jiffies(9) one 💅 — and it's literally just about turning a timespec64 into jiffies. that's it. that's the whole vibe. let's get into it 🎀

🌸 NAME 🌸

timespec64_to_jiffies — convert a timespec64 value to jiffies 🦋

✨ SYNOPSIS ✨

unsigned long timespec64_to_jiffies (const struct timespec64 *value );

🍓 ARGUMENTS 🍓

  • value — pointer to struct timespec64. that's your input, bestie, it's a pointer, don't forget the * 🙈

💖 DESCRIPTION 💖

so like, the TICK_NSEC - 1 rounds the value up to the next resolution. that's the whole trick ✨

and listen — a remainder subtract here would NOT do the right thing, because the resolution values don't fall on second boundaries. so like, this line:

nsec -= nsec % TICK_NSEC;

is NOT a correct resolution rounding. periodt. 💀

also quick heads up: because of the small error in the multiplier here, this rounding is incorrect for sufficiently large values of tv_nsec — but well formed timespecs should have tv_nsec < NSEC_PER_SEC, so we're OK 🫶 (vibe check passed, ngl).

rather, we just shift the bits off the right 👑

and the >> (NSEC_JIFFIE_SC - SEC_JIFFIE_SC) is what converts the scaled nsec value to a scaled second value. that's the conversion, lowkey iconic 🌈

🔥 RETURN 🔥

jiffies value ⭐

👑 SEE ALSO 👑

Kernel file ./kernel/time/time.c, plus the whole friend group:

and that's the whole page, bestie 🧚 go convert some timespecs, you got this 💜

this one lives in ./kernel/time and it's the October 2026 edition of the Kernel API Manual — mwah, catch you in the next manpage 💋💖
📦 where this page comes from