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USCHED_SET(2)            DragonFly System Calls Manual           USCHED_SET(2)


NAME

     usched_set -- setting up a proc's usched


LIBRARY

     Standard C Library (libc, -lc)


SYNOPSIS

     #include <sys/types.h>
     #include <sys/usched.h>

     int
     usched_set(pid_t pid, int cmd, void *data, int bytes);


DESCRIPTION

     The usched_set() function is used to perform several user scheduler
     tasks.  These tasks include: setting the user scheduler, assigning an LWP
     to a specific CPU, adding a CPU to the available CPUs for an LWP, and
     removing a CPU from the list of available CPUs for an LWP.  The
     usched_set() function requires superuser privileges for all commands
     except USCHED_GET_CPU and USCHED_GET_CPUMASK.

     The cmd argument specifies the action for usched_set() to take:

     USCHED_SET_SCHEDULER  set the user scheduler where data is a char * that
                           contains the name of the user scheduler.

     USCHED_SET_CPU        assign the LWP to the cpuid pointed to by data.

     USCHED_GET_CPU        copy the LWP's CPU ID to the cpuid pointed to by
                           data.

     USCHED_GET_CPUMASK    copy the LWP's CPU mask to the cpumask_t type
                           pointed to by data.

     USCHED_SET_CPUMASK    set the LWP's CPU mask to the cpumask_t type
                           pointed to by data.

     USCHED_ADD_CPU        add the cpuid specified by data to the list of
                           available CPUs for the LWP.

     USCHED_DEL_CPU        remove the cpuid specified by data from the list of
                           available CPUs for the LWP.


RETURN VALUES

     Upon successful completion, the value 0 is returned; otherwise the
     value -1 is returned and the global variable errno is set to indicate the
     error.


ERRORS

     The function will fail if:

     [EINVAL]           The user scheduler to set is not in the list of
                        available user schedulers.  The bytes argument is not
                        the correct size (int) for a cpuid.  The specified
                        cpuid is not set in smp_active_mask.  Cmd contains an
                        unknown value.

     [EFBIG]            The specified cpuid is not a valid cpuid for the
                        system.

     [EPERM]            Deleting the specified cpuid leaves the LWP without a
                        CPU to run on.


SEE ALSO

     usched(8)


HISTORY

     The usched_set() function call was added in DragonFly 1.9.


AUTHORS

     The usched_set() system call was written by Matt Dillon.  This manual
     page was written by Joe Talbott.


BUGS

     Only pid equals current LWP PID or 0 is implemented.  The current LWP PID
     is used for pid when pid is 0.  One would normally only use 0 for pid.

DragonFly 4.7                   January 9, 2017                  DragonFly 4.7

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