usecs_to_jiffies(9)

💅 usecs_to_jiffies (Kernel API Manual)

Ok so bestie, buckle up — this one lives in the Kernel API Manual and it's literally the glow-up translator for time units. It takes microseconds and turns them into jiffies. Slay.

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✨ NAME ✨

usecs_to_jiffies — convert microseconds to jiffies 🕐➡️🎀

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🌸 SYNOPSIS 🌸

unsigned long usecs_to_jiffies (const unsigned int u );

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🦋 ARGUMENTS 🦋

• u — the time, in microseconds. That's it, that's the whole input. 🍓

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💖 DESCRIPTION 💖

So the conversion is done as follows, bestie — pay attention, this is the whole vibe:

• MAX_JIFFY_OFFSET values] mean 'infinite timeout' too.
• all other values are converted to jiffies by either multiplying the input value by a factor or dividing it with a factor and handling any 32-bit overflows as for msecs_to_jiffies.

usecs_to_jiffies checks for the passed in value being a constant via __builtin_constant_p, which is honestly iconic of it — it lets gcc eliminate most of the code. 🔥

Then __usecs_to_jiffies gets called if the value passed does not allow constant folding and the actual conversion must be done at runtime. And the HZ range specific helpers _usecs_to_jiffies are called both directly here and from __msecs_to_jiffies in the case where constant folding is not possible. The way this thing multitasks 😭👑

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👑 RETURN 👑

The jiffies value. 💫

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🌈 SEE ALSO 🌈

Kernel file ./include/linux/jiffies.h, plus the whole friend group:

• get_jiffies_64(9)
• General information about time_* inlines(9)
• time_after(9)
• time_before(9)
• time_after_eq(9)
• time_before_eq(9)
• time_in_range(9)
• time_in_range_open(9)
• time_after64(9)
• time_before64(9)
• time_after_eq64(9)
• time_before_eq64(9)
• time_in_range64(9)
• time_is_before_jiffies(9)
• time_is_before_jiffies64(9)
• time_is_after_jiffies(9)
• time_is_after_jiffies64(9)
• time_is_before_eq_jiffies(9)
• time_is_before_eq_jiffies64(9)
• time_is_after_eq_jiffies(9)
• time_is_after_eq_jiffies64(9)
• jiffies_to_msecs(9)
• jiffies_to_usecs(9)
• jiffies_to_nsecs(9)
• msecs_to_jiffies(9)
• secs_to_jiffies(9)

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🫶 Ok that's the whole page! This little gem comes from ./include/linux, dated October 2026, and it's filed under usecs_to_jiffies(9). Go forth and convert, bestie — no cap, you got this. 💜✨