# __ppc_set_ppr_med

## 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
    


## LIBRARY



           Standard C library (_libc_ , _-lc_)
    


## 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.
    


## 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**()             │               │         │
           └──────────────────────────────────────┴───────────────┴─────────┘
    


## STANDARDS



           GNU.
    


## 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**.
    


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