NAME

       Csched - LCG Scheduling inferface

SYNOPSIS

       #include <Csched_api.h>

       int Csched_getschedparam(int cid, int *policy, Csched_param_t *param);

       int Csched_setschedparam(int cid, int policy, Csched_param_t *param);

       int Csched_get_priority_min(int policy);

       int Csched_get_priority_mid(int policy);

       int Csched_get_priority_max(int policy);

ERRORS

       Beyond  the  errno  value,  Csched  is setting the serrno value to generic values that are
       described in Cthread(1).

DESCRIPTION

       Csched is a common API interface for scheduling of multithreaded programs.

       Csched_getschedparam retrieves the current scheduling policy and priority  of  the  thread
       referenced with Cthread's id cid.  The policy can be CSCHED_OTHER, CSCHED_FIFO, CSCHED_RR,
       CSCHED_FG_NP or CSCHED_BG_NP.  The param structure contains a member, named sched_priority
       ,  where  will  be  stored the current priority of the thread you ask for. Please read the
       NOTES section.

       Return value is 0 on success, or -1 on error.

       Csched_setschedparam sets the scheduling policy and priority of the thread referenced with
       Cthread's id cid.  The policy can be CSCHED_OTHER, CSCHED_FIFO, CSCHED_RR, CSCHED_FG_NP or
       CSCHED_BG_NP.  You are neverthless warned that the recommended scheduling is CSCHED_OTHER.
       Trying  to  use another scheduling is an opendoor to processor deadlock if you do not code
       with extreme care. Furthermore, except CSCHED_OTHER , it is not guaranteed that the  other
       possible  values  (  CSCHED_CSCHED_FIFO,  CSCHED_RR,  CSCHED_FG_NP  or  CSCHED_BG_NP ) are
       supported or implemented on your platform.  The param structure contains a  member,  named
       sched_priority  ,  where is given the priority of the thread you want the attributes to be
       modified.    Its    value    can    vary    from    Csched_get_priority_min(policy)     to
       Csched_get_priority_max(policy).  Please read the NOTES section.

       Return value is 0 on success, or -1 on error.

       Csched_get_priority_min, Csched_get_priority_mid and Csched_get_priority_max are returning
       the minimum, medium and maximum allowed priorities, respectively, vs.  the  given  policy.
       The  output  is  the  one  that you use in the sched_priority member of the Csched_param_t
       structure. Please read the NOTES section.

       Return value is != -1 on success, or -1 on error.

NOTES

       About scheduling, the  Csched  interface  defines  CSCHED_OTHER,  CSCHED_FIFO,  CSCHED_RR,
       CSCHED_FG_NP  and  CSCHED_BG_NP  for  portability issue. This does not mean that all those
       schedulings are supported on  the  platform  you  are  running  on.  In  particular,  only
       CSCHED_OTHER is officially supported everywhere. The other scheduling policies are totally
       system dependent and do not conform to any standardisation. Please be  aware,  also,  that
       using a scheduling other than CSCHED_OTHER is an opendoor to processor deadlock...

       Finally, on some OSes, the scheduling interfaces are not necessarly in the thread library,
       nor in the C library. In particular, on Digital you may find them in librt, and on Solaris
       in libposix4.

SEE ALSO

       Cthread

AUTHOR

       LCG Grid Deployment Team