The Linux Programming Interface

35PROCESS PRIORITIES AND SCHEDULING

This chapter discusses various system calls and process attributes that determine when and which processes obtain access to the CPU(s). We begin by describing the nice value, a process characteristic that influences the amount of CPU time that a process is allocated by the kernel scheduler. We follow this with a description of the POSIX realtime scheduling API. This API allows us to define the policy and priority used for scheduling processes, giving us much tighter control over how processes are allocated to the CPU. We conclude with a discussion of the system calls for setting a process’s CPU affinity mask, which determines the set of CPUs on which a process running on a multiprocessor system will run.