__PPC_SET_PPR_MED(3)       LinuxProgrammer's Manual       __PPC_SET_PPR_MED(3)

       __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  Prior-
       ity Register

       #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);

       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

       *  __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.

       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.

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

       |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()   |               |         |

       These functions are nonstandard GNU extensions.

       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.


       Power ISA, Book II - Section 3.1 (Program Priority Registers)

       This  page  is  part of release 5.05 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

GNU C Library                     2017-09-15              __PPC_SET_PPR_MED(3)
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