geopm_sched(3) – interface with Linux scheduler

Synopsis

Link with -lgeopm (MPI) or -lgeopm (non-MPI)

int geopm_sched_num_cpu(void);

int geopm_sched_get_cpu(void);

int geopm_sched_proc_cpuset(int num_cpu,
                            cpu_set_t *proc_cpuset);

int geopm_sched_woomp(int num_cpu, cpu_set_t *woomp);

Description

The geopm_sched.h header defines GEOPM interfaces for interacting with the Linux scheduler.

geopm_sched_num_cpu(): Returns the number of online Linux logical CPUs on the system.
geopm_sched_get_cpu(): Returns the Linux logical CPU index that the calling thread is executing on.
geopm_sched_proc_cpuset(): Provides a CPU_SET(3) bit mask identifying the Linux logical CPUs on which the calling process is allowed to run. The user must allocate the bit array proc_cpuset prior to calling this function, and the number of bits allocated is given by the num_cpu parameter. All of the bits in proc_cpuset will be zeroed except for the offsets corresponding to CPUs that the process has access to which will be set to one. Returns zero on success and an error code on failure.
geopm_sched_woomp(): Sets the CPU_SET(3) given by woomp such that it includes all CPUs not used in an OpenMP parallel region but available to the calling thread. If there are no CPU’s that are part of the mask returned by sched_getaffinity(2) but not affinitized by an OpenMP thread then the returned mask will have all bits set, allowing the Linux scheduler to dynamically affinitize the thread. The CPU mask woomp that is created by this function can be used with pthread_attr_setaffinity_np(3) to modify the attributes passed to geopm_ctl_pthread() so that the pthread created is affinitized to CPUs that do not have an OpenMP thread affinity. The mask generated when OpenMP threads are not statically affinitized is unreliable (i.e. use OMP_PROC_BIND environment variable). The num_cpu parameter specifies size of the CPU_SET in terms of number of CPUs. If an error occurs a non-zero error number is returned. See geopm_error(3) for a full description of the error numbers and how to convert them to strings.

geopm_sched(3) – interface with Linux scheduler

Synopsis

Description

See Also