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 (), __ppc_set_ppr_very_low (), __ppc_set_ppr_low (),
__ppc_set_ppr_med_low (), __ppc_set_ppr_med_high () |
Thread safety |
MT-Safe |
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 4.10 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/.