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