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 resources 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(),       │ Thread safety │ MT-Safe │
       │__ppc_set_ppr_very_low(),  │               │         │
       │__ppc_set_ppr_low(),       │               │         │
       │__ppc_set_ppr_med_low(),   │               │         │
       │__ppc_set_ppr_med_high()   │               │         │
       └───────────────────────────┴───────────────┴─────────┘

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)

COLOPHON

       This  page  is  part of release 4.15 of the Linux man-pages project.  A description of the
       project, information about reporting bugs, and the latest version of  this  page,  can  be
       found at https://www.kernel.org/doc/man-pages/.