PREEMPT(9) BSD Kernel Developer's Manual PREEMPT(9)NAMEpreempt, yield -- general preempt and yield functionsSYNOPSIS#include <sys/sched.h> void preempt(void); #include <sys/proc.h> void yield(void);DESCRIPTIONThe preempt() function puts the current LWP back on the system run queue and performs an involuntary context switch. The yield() function is mostly same as preempt(), except that it performs a voluntary context switch. These functions drop the kernel lock before switching and re-acquire it before returning.BSDJuly 3, 2007 BSD