__ppc_set_ppr_med(3)

💅 __ppc_set_ppr_med(3) — Library Functions Manual

okay bestie, gather round, because we're about to talk about the Program Priority Register and honestly? it's giving main character energy on Power architecture. this page lives in the Library Functions Manual, and it's your one-stop group chat for the whole __ppc_set_ppr_* squad. 🫶

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✨ NAME ✨

__ppc_set_ppr_med, __ppc_set_ppr_very_low, __ppc_set_ppr_low, __ppc_set_ppr_med_low, __ppc_set_ppr_med_high — set the Program Priority Register, no cap 💅

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📚 LIBRARY 📚

Standard C library (libc, -lc) — the classic, the icon, the one you already link against. 🎀

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🦋 SYNOPSIS 🦋

#include <sys/platform/ppc.h>

void __ppc_set_ppr_med(void);
void __ppc_set_ppr_very_low(void);
void __ppc_set_ppr_low(void);
void __ppc_set_ppr_med_low(void);
void __ppc_set_ppr_med_high(void);

five little void functions, zero arguments, maximum vibes. ✨

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💖 DESCRIPTION 💖

so these functions are your backstage pass to the Program Priority Register (PPR) on the Power architecture. 🔥

the PPR is a 64-bit register that controls the program's priority. by adjusting the PPR value, the programmer may improve system throughput by causing system resources to be used more efficiently — especially in contention situations. literally the register that says "hey, me first" but politely, and the OS is like "okay bet." 👑

the available unprivileged states are covered by these iconic functions:

• __ppc_set_ppr_med() — sets the Program Priority Register value to medium (which is, btw, the default). the baseline. the vanilla latte of priorities. ☕
• __ppc_set_ppr_very_low() — sets the Program Priority Register value to very low. bestie is taking a nap in the back of the queue. 😴
• __ppc_set_ppr_low() — sets the Program Priority Register value to low. still napping, just slightly less. 💤
• __ppc_set_ppr_med_low() — sets the Program Priority Register value to medium low. a little nap. a lil snooze. 🍓

and then there's the privileged state medium high, which — plot twist — may also be set during certain time intervals by problem-state (unprivileged) programs, using this one:

• __ppc_set_ppr_med_high() — sets the Program Priority to medium high. she's climbing. she's ascending. for a limited time only. 🌈

⚠️ okay serious moment: if the program priority is medium high when the time interval expires, or if an attempt is made to set the priority to medium high when it is not allowed, the priority is set to medium. so no, you can't just live up there forever. the clock is ticking fr fr. 💀

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🎀 ATTRIBUTES 🎀

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

• Interface: __ppc_set_ppr_med(), __ppc_set_ppr_very_low(), __ppc_set_ppr_low(), __ppc_set_ppr_med_low(), __ppc_set_ppr_med_high() — Attribute: Thread safety — Value: MT-Safe 🧚

(yes, all five of them. one big happy MT-Safe family. the table said so and the table never lies. 💜)

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⭐ STANDARDS ⭐

GNU. that's it. that's the standard. 💅

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🌸 HISTORY 🌸

the lore, bestie, we have the lore:

• __ppc_set_ppr_med()
• __ppc_set_ppr_low()
• __ppc_set_ppr_med_low()

→ these three are glibc 2.18 girlies. vintage. iconic. 🎀

• __ppc_set_ppr_very_low()
• __ppc_set_ppr_med_high()

→ and these two arrived later, in glibc 2.23. late bloomers but they ATE. ✨

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🔥 NOTES 🔥

important detail, don't skip:

the functions __ppc_set_ppr_very_low() and __ppc_set_ppr_med_high() will be defined by <sys/platform/ppc.h> if _ARCH_PWR8 is defined.

and you can test availability of these functions using:

#ifdef _ARCH_PWR8

so like, vibe check your macros before you call them, iykyk. 😭

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👀 SEE ALSO 👀

• __ppc_yield(3)
• Power ISA, Book II - Section 3.1 (Program Priority Registers)

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and that's the whole page, bestie!! this was Linux man-pages 6.20, dated 2026-02-08, page __ppc_set_ppr_med(3), signing off with a little kiss 🫶💖 go forth and set your program priority responsibly, mlm (much love, medium). 🌟