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NetBSD 6.1.5 - man page for cpu_need_resched (netbsd section 9)

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

NAME
     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 pro-
     cessor, 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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