__round_jiffies_relative(9)

✨ __round_jiffies_relative ✨

okay so bestie, this is a page from the Kernel API Manual (section 9, the kernel-functions girlies) and it's all about __round_jiffies_relative — literally a function to round jiffies to a full second 💅

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🎀 NAME 🎀

__round_jiffies_relative — function to round jiffies to a full second ⏰✨

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🌸 SYNOPSIS 🌸

unsigned long __round_jiffies_relative (unsigned long j , int cpu );

that's the whole vibe, no cap 🫶

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🦋 ARGUMENTS 🦋

• j — the time in (relative) jiffies that should be rounded 💖 like, this is the number we're about to glow up.
• cpu — the processor number on which the timeout will happen 👑 gotta know which CPU is showing up to the party.

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🔥 DESCRIPTION 🔥

okay so here's the tea ☕ — __round_jiffies_relative takes a time delta in the future (in jiffies) and rounds it up or down to (approximately) full seconds. it's giving "close enough is iconic" ✨

this is lowkey so useful for timers where the exact time they fire does not matter too much, as long as they fire approximately every X seconds. main character timers only 💅

by rounding these timers to whole seconds, all such timers will fire at the same time, rather than at various times spread out. the whole goal here? have the CPU wake up less, which saves power 🔋🌱 periodt, we love an eco-friendly queen.

the exact rounding is skewed for each processor so we don't get all processors firing at the exact same time 😭 because that could lead to lock contention or spurious cache line bouncing 💀 (iykyk, that's a big yikes).

the return value is the rounded version of the j parameter 🎁 that's it, that's the gift.

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🌈 SEE ALSO 🌈

go check these out bestie, the whole friend group 🫶:

• Kernel file ./kernel/time/timer.c struct timer_base(9)
• round_jiffies(9)
• round_jiffies_relative(9)
• __round_jiffies_up_relative(9)
• round_jiffies_up(9)
• round_jiffies_up_relative(9)
• timer_init_key(9)
• mod_timer_pending(9)
• mod_timer(9)
• timer_reduce(9)
• add_timer(9)
• add_timer_local(9)
• add_timer_global(9)
• add_timer_on(9)
• __timer_delete(9)
• timer_delete(9)
• timer_shutdown(9)
• __try_to_del_timer_sync(9)
• timer_delete_sync_try(9)
• __timer_delete_sync(9)
• timer_delete_sync(9)
• timer_shutdown_sync(9)
• fetch_next_timer_interrupt_remote(9)
• timer_unlock_remote_bases(9)
• timer_lock_remote_bases(9)
• timer_base_is_idle(9)
• timer_expire_remote(9)
• get_next_timer_interrupt(9)
• timer_base_try_to_set_idle(9)
• timer_clear_idle(9)
• __run_timers(9)

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💖 ngl, that's the whole page! go round some jiffies, bestie, you got this 💪✨

and that's a wrap, babes 🎬 — this lil number lives in ./kernel/time, dated October 2026, and it's from the __round_jiffies_relative(9) era of the Kernel API Manual. slay, bye 💅🦋