proc_pid_timerslack_ns(5)

💖 NAME 💖

/proc/pid/timerslack_ns — timer slack but make it nanoseconds, bestie ✨

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🦋 DESCRIPTION 🦋

/proc/pid/timerslack_ns</p> (since Linux 4.6) 🎀

Okay so this file right here? It's the little window into a process's "current" timer slack value, and it's expressed in nanoseconds. Slay. 💅

And the tea is: it's writable. So not only can you peek at the process's timer slack value, you can literally change it. Main character energy fr.

Now listen — if you write 0 to this file, it resets the "current" timer slack back to the "default" timer slack value. That's the whole vibe. 🌸

For further details, go read the discussion of PR_SET_TIMERSLACK in prctl(2). iykyk. 👑

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the permission lore (it's giving glow-up) 🌈

So initially, permission to access this file was governed by a ptrace access mode PTRACE_MODE_ATTACH_FSCREDS check — see ptrace(2) if you wanna read up.

But then everyone was like... bestie why is this so strict 😭 and it was subsequently deemed too strict a requirement. And there was a whole side effect too: requiring a process to have the CAP_SYS_PTRACE capability would also allow it to view and change any process's memory. Not it. 💀

Therefore, since Linux 4.9, only the (weaker) CAP_SYS_NICE capability is required to access this file. Glow-down of permissions, in the best possible way. ✨

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🌟 SEE ALSO 🌟

• proc(5)

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k bye bestie, go read your process's timer slack and go off 💖 This was page proc_pid_timerslack_ns(5) from the File Formats Manual, brought to you by Linux man-pages 6.20, dated 2026-02-08. Stan. 🫶🎀