bionic (3) __ppc_set_ppr_low.3.gz

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/.