sched_get_priority_max(2)

💖 sched_get_priority_max(2) — the System Calls Manual girlies' edition 💖

okay bestie so this is a page from the System Calls Manual (that's section 2, iykyk) and it's all about sched_get_priority_max and its lil sibling sched_get_priority_min. two functions, one job: telling you the priority range. slay.

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✨ NAME ✨

sched_get_priority_max, sched_get_priority_min — get static priority range 🎀

📚 LIBRARY 📚

Standard C library, aka libc, link it with -lc. no cap.

🦋 SYNOPSIS 🦋

#include <sched.h>

int sched_get_priority_max(int policy);
int sched_get_priority_min(int policy);

look at that. two lil ints in, two lil ints out. iconic.

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💅 DESCRIPTION 💅

so, the vibes: sched_get_priority_max() hands you back the maximum priority value you can use with the scheduling algorithm that the policy argument identifies. sched_get_priority_min() does the same thing but for the minimum priority value. same policy, opposite end of the range. bestie behavior.

the policy values that are supported are:

• SCHED_FIFO
• SCHED_RR
• SCHED_OTHER
• SCHED_BATCH
• SCHED_IDLE
• SCHED_DEADLINE

if you want the whole lore on what each of those policies actually does, go read sched(7). it's giving required reading.

kay so here's the key thing to internalize: processes with numerically higher priority values get scheduled before processes with numerically lower priority values. so obviously the value from sched_get_priority_max() is gonna be greater than the value from sched_get_priority_min(). that's just math, bestie. 💀

on Linux, the static priority range is 1 to 99 for the SCHED_FIFO and SCHED_RR policies, and priority 0 for all the remaining policies. and no, you cannot alter the scheduling priority ranges for the various policies. they're locked in. periodt. 🔒

now here's the portable-apps tea ☕ the range of scheduling priorities may vary on other POSIX systems. so if you want your app to work everywhere, the good move is to use a virtual priority range and map it onto the interval you got from sched_get_priority_max() and sched_get_priority_min(). and btw, POSIX.1 requires a spread of at least 32 between the maximum and the minimum values for SCHED_FIFO and SCHED_RR. so no teeny tiny ranges, okay?

oh and one more: POSIX systems where sched_get_priority_max() and sched_get_priority_min() are available define _POSIX_PRIORITY_SCHEDULING in <unistd.h>. that's your little signal that the functions exist. a vibe check, if you will. 👑

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🌈 RETURN VALUE 🌈

on success, sched_get_priority_max() and sched_get_priority_min() return the maximum/minimum priority value for the named scheduling policy. yay!! 🫶

on error, -1 is returned, and errno is set to indicate the error. so like, check your errno bestie, don't just stare at the -1. 😭

💀 ERRORS 💀

• EINVAL — the argument policy does not identify a defined scheduling policy. basically you passed it something that isn't on the list. it's not a vibe, it's an error.

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⭐ STANDARDS ⭐

POSIX.1-2024. we stan a modern standard.

🌸 HISTORY 🌸

POSIX.1-2001. it's been here since the early 2000s and it's still eating, honestly.

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👀 SEE ALSO 👀

• sched_getaffinity(2)
• sched_getparam(2)
• sched_getscheduler(2)
• sched_setaffinity(2)
• sched_setparam(2)
• sched_setscheduler(2)
• sched(7)

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and that's the whole page, bestie!! mwah 💖 this was Linux man-pages 6.20, dated 2026-02-08 — go drink some water, go check your priorities (literally, via sched_get_priority_max()), and stay iconic. bye!! 🎀✨🦋