sched_setscheduler - set scheduling policy and scheduling parameters
#include <sched.h>
int sched_setscheduler(pid_t pid, int policy,
const struct sched_param *param);
The sched_setscheduler() function sets the scheduling policy and
scheduling parameters of the process specified by pid to policy
and the parameters specified in the sched_param structure pointed to by
param, respectively. The value of the sched_priority member in
the sched_param structure is any integer within the inclusive priority
range for the scheduling policy specified by policy. The
sched_setscheduler() function ignores the other members of the
sched_param structure. If the value of pid is negative, the
behavior of the sched_setscheduler() function is unspecified.
The possible values for the policy parameter are defined in
the header <sched.h> (see sched.h(3HEAD)):
If a process specified by pid exists and if the calling
process has permission, the scheduling policy and scheduling parameters are
set for the process whose process ID is equal to pid. The real
or effective user ID of the calling process must match the real or
saved (from exec(2)) user ID of the target process unless the
effective user ID of the calling process is 0. See
Intro(2).
If pid is 0, the scheduling policy and scheduling
parameters are set for the calling process.
To change the policy of any process to either of the real
time policies SCHED_FIFO or SCHED_RR, the calling process must
either have the SCHED_FIFO or SCHED_RR policy or have an
effective user ID of 0.
The sched_setscheduler() function is considered successful
if it succeeds in setting the scheduling policy and scheduling parameters of
the process specified by pid to the values specified by policy
and the structure pointed to by param, respectively.
Upon successful completion, the function returns the former scheduling policy of
the specified process. If the sched_setscheduler() function fails to
complete successfully, the policy and scheduling parameters remain unchanged,
and the function returns −1 and sets errno to indicate the
error.
The sched_setscheduler() function will fail if:
EINVAL
The value of policy is invalid, or one or more of
the parameters contained in param is outside the valid range for the
specified scheduling policy.
EPERM
The requesting process does not have permission to set
either or both of the scheduling parameters or the scheduling policy of the
specified process.
ESRCH
No process can be found corresponding to that specified
by pid.
See attributes(7) for descriptions of the following attributes:
| ATTRIBUTE
TYPE |
ATTRIBUTE VALUE |
| Interface Stability |
Committed |
| MT-Level |
MT-Safe |
| Standard |
See standards(7). |
priocntl(1), Intro(2), exec(2), priocntl(2),
sched_get_priority_max(3C), sched_getparam(3C),
sched_getscheduler(3C), sched_setparam(3C),
sched.h(3HEAD), librt(3LIB), attributes(7),
standards(7)