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Top Forums UNIX for Advanced & Expert Users SCHED_SPORADIC explained? help needed Post 302138500 by Perderabo on Tuesday 2nd of October 2007 03:32:41 AM
Old 10-02-2007
SS is certainly not an additional thread. It is one of several scheduling policies that affect the behavior of the scheduler. The scheduler is part of the kernel and you may be using the term dispatcher instead. Which term you use is not important as long as you understand that the scheduler adjusts the priorities of the threads as well as finding one to run in an available cpu. See this link: The QNX Neutrino Microkernel which has the best description I have seen on sporadic scheduling.

I have never used it so i can't add too much. All threads contain the sched_param struct, but the elements pertaining to sporadic scheduling are ignored if sporadic scheduling is not in use.
 
PTHREAD_ATTR_SETINHERITSCHED(3) 			     Linux Programmer's Manual				   PTHREAD_ATTR_SETINHERITSCHED(3)

NAME
pthread_attr_setinheritsched, pthread_attr_getinheritsched - set/get inherit scheduler attribute in thread attributes object SYNOPSIS
#include <pthread.h> int pthread_attr_setinheritsched(pthread_attr_t *attr, int inheritsched); int pthread_attr_getinheritsched(pthread_attr_t *attr, int *inheritsched); Compile and link with -pthread. DESCRIPTION
The pthread_attr_setinheritsched() function sets the inherit scheduler attribute of the thread attributes object referred to by attr to the value specified in inheritsched. The inherit scheduler attribute determines whether a thread created using the thread attributes object attr will inherit its scheduling attributes from the calling thread or whether it will take them from attr. The following values may be specified in inheritsched: PTHREAD_INHERIT_SCHED Threads that are created using attr inherit scheduling attributes from the creating thread; the scheduling attributes in attr are ignored. PTHREAD_EXPLICIT_SCHED Threads that are created using attr take their scheduling attributes from the values specified by the attributes object. The default setting of the inherit scheduler attribute in a newly initialized thread attributes object is PTHREAD_INHERIT_SCHED. The pthread_attr_getinheritsched() returns the inherit scheduler attribute of the thread attributes object attr in the buffer pointed to by inheritsched. RETURN VALUE
On success, these functions return 0; on error, they return a nonzero error number. ERRORS
pthread_attr_setinheritsched() can fail with the following error: EINVAL Invalid value in inheritsched. POSIX.1-2001 also documents an optional ENOTSUP error ("attempt was made to set the attribute to an unsupported value") for pthread_attr_setinheritsched(). CONFORMING TO
POSIX.1-2001. BUGS
As at glibc 2.8, if a thread attributes object is initialized using pthread_attr_init(3), then the scheduling policy of the attributes object is set to SCHED_OTHER and the scheduling priority is set to 0. However, if the inherit scheduler attribute is then set to PTHREAD_EXPLICIT_SCHED, then a thread created using the attribute object wrongly inherits its scheduling attributes from the creating thread. This bug does not occur if either the scheduling policy or scheduling priority attribute is explicitly set in the thread attributes object before calling pthread_create(3). EXAMPLE
See pthread_setschedparam(3). SEE ALSO
sched_setscheduler(2), pthread_attr_init(3), pthread_attr_setschedparam(3), pthread_attr_setschedpolicy(3), pthread_create(3), pthread_setschedparam(3), pthread_setschedprio(3), pthreads(7) COLOPHON
This page is part of release 3.44 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/. Linux 2012-03-15 PTHREAD_ATTR_SETINHERITSCHED(3)
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