msecs_to_jiffies(9)

💅 msecs_to_jiffies — a Kernel API Manual moment

okay so bestie, welcome to msecs_to_jiffies(9), straight out of the Kernel API Manual ✨ this is the little function that turns your cute millisecond numbers into jiffies, and she's lowkey doing a LOT of heavy lifting behind the scenes. let's get into it 🫶

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✨ NAME ✨

msecs_to_jiffies — convert milliseconds to jiffies 💖

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🌸 SYNOPSIS 🌸

unsigned long msecs_to_jiffies (const unsigned int m );

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🎀 ARGUMENTS 🎀

• m — time in milliseconds ⏱️ that's it, that's the whole input, she's simple like that

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🦋 DESCRIPTION 🦋

okay so the conversion is done as follows, no cap:

• negative values mean 'infinite timeout' (MAX_JIFFY_OFFSET) ♾️
• MAX_JIFFY_OFFSET values] mean 'infinite timeout' too 👀 (yes bestie, that's exactly how the page says it, i'm not touching it)
• 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 💀 for the details see _msecs_to_jiffies

now the actually iconic part: msecs_to_jiffies checks for the passed in value being a constant via __builtin_constant_p allowing gcc to eliminate most of the code 🔥 like she literally gets compiled away, main character energy fr.

__msecs_to_jiffies is 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 _msecs_to_jiffies are called both directly here and from __msecs_to_jiffies in the case where constant folding is not possible. iykyk 💅

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⭐ RETURN ⭐

jiffies value 👑

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🌈 SEE ALSO 🌈

• Kernel file ./include/linux/jiffies.h
• 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)
• secs_to_jiffies(9)
• usecs_to_jiffies(9)

like she has a whole friend group, we love a connected queen 🧚‍♀️💜

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and that's the whole page bestie, mwah 💋 this one lives in ./include/linux and the version stamp says October 2026 — so yeah, future icon behavior, periodt 🎀✨👑