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cpu_idle(9) [netbsd man page]

CPU_IDLE(9)						   BSD Kernel Developer's Manual					       CPU_IDLE(9)

cpu_idle -- machine-dependent processor idling interface SYNOPSIS
#include <sys/cpu.h> void cpu_idle(void); DESCRIPTION
cpu_idle() is called by machine-independent code when the processor has nothing to do. It can be used to conserve the processor power, for example. cpu_idle() returns immediately if cpu_need_resched() has been called for the processor after the last call of cpu_idle() or cpu_did_resched() on the processor. cpu_idle() returns as soon as possible when cpu_need_resched() is called for the processor. Otherwise, it returns when- ever it likes. cpu_idle() is called at IPL_NONE, without any locks held. EXAMPLES
The simplest (and, in some cases, the best) implementation of cpu_idle() is the following. void cpu_idle(void) { /* nothing */ } SEE ALSO
cpu_need_resched(9), cpu_switchto(9), intro(9), spl(9) BSD
April 20, 2007 BSD

Check Out this Related Man Page

CPU_NEED_RESCHED(9)					   BSD Kernel Developer's Manual				       CPU_NEED_RESCHED(9)

cpu_need_resched -- context switch notification SYNOPSIS
#include <sys/cpu.h> void cpu_need_resched(struct cpu_info *ci, int flags); DESCRIPTION
The cpu_need_resched() function is the machine-independent interface for the scheduler to notify machine-dependent code that a context switch from the current LWP, on the cpu ci, is required. This event may occur if a higher priority LWP appears on the run queue or if the current LWP has exceeded its time slice. If RESCHED_KPREEMPT flag is specified in flags and __HAVE_PREEMPTION C pre-processor macro is defined in <machine/intr.h>, machine-dependent code should make a context switch happen as soon as possible even if the cpu is running the kernel code. If RESCHED_IMMED flag is specified in flags, machine-dependent code should make a context switch happen as soon as possible. In that case, for example, if ci is not the current processor, cpu_need_resched() typically issues an inter processor call to the processor to make it notice the need of a context switch as soon as possible. Typically, the cpu_need_resched() function will perform the following operations: o Set a per-processor flag which is checked by userret(9) when returning to user-mode execution. o Post an asynchronous software trap (AST). o Send an inter processor interrupt to wake up cpu_idle(9). SEE ALSO
sched_4bsd(9), userret(9) BSD
July 31, 2010 BSD
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