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csched(3) [debian man page]

CSCHED(3)						     Common Library Functions							 CSCHED(3)

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_prior-
       ity_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 priori-
       ties, 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  offi-
       cially  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

LCG
					       $Date: 2010-04-05 09:51:26 +0200 (Mon, 05 Apr 2010) $					 CSCHED(3)

Check Out this Related Man Page

pthread_getschedparam(3C)												 pthread_getschedparam(3C)

NAME

       pthread_getschedparam, pthread_setschedparam - access dynamic thread scheduling parameters

SYNOPSIS

       cc -mt [ flag... ] file... -lpthread [ library... ]
       #include <pthread.h>

       int pthread_getschedparam(pthread_t thread, int *restrict policy, struct sched_param *restrict param);

       int pthread_setschedparam(pthread_t thread, int policy, const struct sched_param *param);

       The  pthread_getschedparam()  and  pthread_setschedparam()  functions  allow  the scheduling policy and scheduling parameters of individual
       threads within a multithreaded process to be retrieved and  set.  Supported  policies  are   SCHED_FIFO,  SCHED_RR,  and  SCHED_OTHER.  See
       pthreads(5).  For SCHED_FIFO, SCHED_RR, and SCHED_OTHER, the affected scheduling parameter is the sched_priority member of the  sched_param
       structure.

       The pthread_getschedparam() function retrieves the scheduling policy and scheduling parameters for the thread whose thread  ID is given	by
       thread  and  stores  those  values in policy and param, respectively. The priority value returned from pthread_getschedparam() is the value
       specified by the most recent pthread_setschedparam() or pthread_create() call affecting the  target  thread,  and  reflects  any  temporary
       adjustments  to	its  priority  as a result of any priority inheritance or ceiling functions. The pthread_setschedparam() function sets the
       scheduling policy and associated scheduling parameters for the thread whose thread  ID is given by thread  to  the  policy  and	associated
       parameters provided in policy and param, respectively.

       If the pthread_setschedparam() function fails, no scheduling parameters will be changed	for the target thread.

       If successful, the pthread_getschedparam() and pthread_setschedparam() functions return	0. Otherwise, an error number is returned to indi-
       cate the error.

       The pthread_getschedparam() function may fail if:

       ESRCH	       The value specified by thread does not refer to a existing thread.

       The pthread_setschedparam() function may fail if:

       EINVAL	       The value specified by policy or one of the scheduling parameters associated with the scheduling policy policy is invalid.

       EPERM	       The caller does not have the appropriate permission to set either the scheduling parameters or the scheduling policy of the
		       specified thread.

       ESRCH	       The value specified by thread does not refer to a existing thread.

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Standard			   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |MT-Safe			   |
       +-----------------------------+-----------------------------+

       pthread_attr_init(3C),	sched_getparam(3RT),   sched_setparam(3RT),   sched_getscheduler(3RT),	 sched_setscheduler(3RT),   attributes(5),
       pthreads(5), standards(5)

								    23 Nov 2005 					 pthread_getschedparam(3C)
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