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__PPC_SET_PPR_MED(3)                                                    LinuxProgrammer's Manual                                                    __PPC_SET_PPR_MED(3)

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

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);

DESCRIPTION
       These functions provide access 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 re‐
       sources to be used more efficiently, especially in contention situations.  The available unprivileged states are covered by the following functions:

       *  __ppc_set_ppr_med() sets the Program Priority Register value to medium (default).

       *  __ppc_set_ppr_very_low() sets the Program Priority Register value to very low.

       *  __ppc_set_ppr_low() sets the Program Priority Register value to low.

       *  __ppc_set_ppr_med_low() sets the Program Priority Register value to medium low.

       The privileged state medium high may also be set during certain time intervals by problem-state (unprivileged) programs, with the following function:

       *  __ppc_set_ppr_med_high() sets the Program Priority to medium high.

       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.

VERSIONS
       The   functions   __ppc_set_ppr_med(),   __ppc_set_ppr_low(),   and   __ppc_set_ppr_med_low()   are   provided  by  glibc  since  version  2.18.   The  functions
       __ppc_set_ppr_very_low() and __ppc_set_ppr_med_high() first appeared in glibc in version 2.23.

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

       ┌──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┬───────────────┬─────────┐
       │Interface                                                                                                                             │ Attribute     │ Value   │
       ├──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┼───────────────┼─────────┤
       │__ppc_set_ppr_med(), __ppc_set_ppr_very_low(), __ppc_set_ppr_low(), __ppc_set_ppr_med_low(), __ppc_set_ppr_med_high()                 │ Thread safety │ MT-Safe │
       └──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┴───────────────┴─────────┘

CONFORMING TO
       These functions are nonstandard GNU extensions.

NOTES
       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.   Availability  of  these
       functions can be tested using #ifdef _ARCH_PWR8.

SEE ALSO
       __ppc_yield(3)

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

GNU C Library                                                                  2021-03-22                                                           __PPC_SET_PPR_MED(3)