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.TH __PPC_SET_PPR_MED 3 2017-09-15 "GNU C Library" "Linux\

Programmer's Manual"

.SH 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

.SH SYNOPSIS

.B #include <sys/platform/ppc.h>

.PP

.B void __ppc_set_ppr_med(void);

.br

.B void __ppc_set_ppr_very_low(void);

.br

.B void __ppc_set_ppr_low(void);

.br

.B void __ppc_set_ppr_med_low(void);

.br

.B void __ppc_set_ppr_med_high(void);

.SH DESCRIPTION

These functions provide access to the

.I Program Priority Register

(PPR) on the Power architecture.

.PP

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:

.IP * 3

.BR __ppc_set_ppr_med ()

sets the Program Priority Register value to

.IR medium

(default).

.IP *

.BR __ppc_set_ppr_very_low ()

sets the Program Priority Register value to

.IR "very low" .

.IP *

.BR __ppc_set_ppr_low ()

sets the Program Priority Register value to

.IR low .

.IP *

.BR __ppc_set_ppr_med_low ()

sets the Program Priority Register value to

.IR "medium low" .

.PP

The privileged state

.IR "medium high"

may also be set during certain time intervals by problem-state (unprivileged)

programs, with the following function:

.IP * 3

.BR __ppc_set_ppr_med_high ()

sets the Program Priority to

.IR "medium high" .

.PP

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.

.SH VERSIONS

The functions

.BR __ppc_set_ppr_med (),

.BR __ppc_set_ppr_low ()

and

.BR __ppc_set_ppr_med_low ()

are provided by glibc since version 2.18.

The functions

.BR __ppc_set_ppr_very_low ()

and

.BR __ppc_set_ppr_med_high ()

first appeared in glibc in version 2.23.

.SH ATTRIBUTES

For an explanation of the terms used in this section, see

.BR attributes (7).

.ad l

.TS

allbox;

lbw26 lb lb

l l l.

Interface	Attribute	Value

T{

.BR __ppc_set_ppr_med (),

.br

.BR __ppc_set_ppr_very_low (),

.br

.BR __ppc_set_ppr_low (),

.br

.BR __ppc_set_ppr_med_low (),

.br

.BR __ppc_set_ppr_med_high ()

T}	Thread safety	MT-Safe

.TE

.ad

.SH CONFORMING TO

These functions are nonstandard GNU extensions.

.SH NOTES

The functions

.BR __ppc_set_ppr_very_low ()

and

.BR __ppc_set_ppr_med_high ()

will be defined by

.I <sys/platform/ppc.h>

if

.B _ARCH_PWR8

is defined.

Availability of these functions can be tested using

.BR "#ifdef _ARCH_PWR8" .

.SH SEE ALSO

.BR __ppc_yield (3)

.PP

.IR "Power ISA, Book\ II - Section\ 3.1 (Program Priority Registers)"

.SH COLOPHON

This page is part of release 4.15 of the Linux

.I 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/.