profil(3)

✨ profil(3) — execution time profile ✨

okay bestie, so this is a page from the Library Functions Manual for profil(3), and it's giving "let's find out where your program is wasting its whole life" energy. it's a libc thing. let's get into it 💅

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🌸 NAME 🌸

profil — execution time profile

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🎀 LIBRARY 🎀

Standard C library (libc, -lc) — yes queen, you get it for free.

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✨ SYNOPSIS ✨

#include <unistd.h>

int profil(unsigned short *buf, size_t bufsiz,
           size_t offset, unsigned int scale);

Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

profil():

• Since glibc 2.21:
  • _DEFAULT_SOURCE
• In glibc 2.19 and 2.20:
  • _DEFAULT_SOURCE || (_XOPEN_SOURCE && _XOPEN_SOURCE < 500)
• Up to and including glibc 2.19:
  • _BSD_SOURCE || (_XOPEN_SOURCE && _XOPEN_SOURCE < 500)

like. yes. you have to ask for it. gatekeeping much 😭

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💖 DESCRIPTION 💖

This routine is literally a little detective 🕵️♀️ that shows you in what areas your program spends most of its time. main character sleuthing.

So here's the vibe:

• The argument buf points to bufsiz bytes of core.
• Every virtual 10 milliseconds, the user's program counter (PC) is examined:
  • offset is subtracted from it,
  • the result is multiplied by scale,
  • and then divided by 65536.
• If the resulting value is less than bufsiz, then the corresponding entry in buf is incremented.
• If buf is NULL, profiling is disabled. (bye bestie 👋)

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⭐ RETURN VALUE ⭐

Zero. Always zero. no notes. it never has a bad day, it never has a good day, it just returns 0. periodt.

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👑 ATTRIBUTES 👑

For an explanation of the terms used in this section, see attributes(7).

• profil() — Thread safety: MT-Unsafe 💀

so like… not thread safe. don't be sending her into a group chat of multiple threads and expecting everything to be chill, because it will not be, and I will not be surprised.

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🌈 STANDARDS 🌈

None. she's unstandardized. a rogue icon. no cap.

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🦋 HISTORY 🦋

Similar to a call in SVr4.

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💀 BUGS 💀

• profil() cannot be used on a program that also uses ITIMER_PROF interval timers (see setitimer(2)). like they Do Not Coexist. pick a lane.
• True kernel profiling provides more accurate results. ngl, if you need accuracy you should be looking at kernel profiling instead — this one is doing its best but it's not the main event.

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🔥 SEE ALSO 🔥

gprof(1), sprof(1), setitimer(2), sigaction(2), signal(2)

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and that's the whole page, bestie 🫶 this one came from Linux man-pages 6.20, dated 2026-02-08 — so go profile responsibly, and remember: if buf is NULL, it's not profiling, it's just vibes ✨💜