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CPU_NEED_RESCHED(9) NetBSD Kernel Developer's Manual CPU_NEED_RESCHED(9)
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by Kimmo Suominen.
Based on man-cgi by Panagiotis Christias.
cpu_need_resched -- context switch notification
cpu_need_resched(struct cpu_info *ci, int flags);
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() typi-
cally 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
· Set a per-processor flag which is checked by userret(9) when
returning to user-mode execution.
· Post an asynchronous software trap (AST).
· Send an inter processor interrupt to wake up cpu_idle(9).
NetBSD 9.2 July 31, 2010 NetBSD 9.2