最佳答案
本地定时器中断是在APIC上实现的定时器,它仅中断特定cpu,而不是引发可由任何cpu处理的中断.它在Bovet& amp; Cesati的“了解Linux内核”.一个片段：
The local APIC present in recent 80×86 microprocessors (see the
section “Interrupts and Exceptions” in Chapter 4) provides yet another
time-measuring device: the cpu local timer.The cpu local timer is a device similar to the Programmable Interval
Timer just described that can issue one-shot or periodic interrupts.
There are,however,a few differences:
- The APIC’s timer counter is 32 bits long,while the PIT’s timer counter is 16 bits long; therefore,the local timer can be programmed
to issue interrupts at very low frequencies (the counter stores the
number of ticks that must elapse before the interrupt is issued).- The local APIC timer sends an interrupt only to its processor,while the PIT raises a global interrupt,which may be handled by any
cpu in the system.- The APIC’s timer is based on the bus clock signal (or the APIC bus signal,in older machines). It can be programmed in such a way to
decrease the timer counter every 1,2,4,8,16,32,64,or 128 bus
clock signals. Conversely,the PIT,which makes use of its own clock
signals,can be programmed in a more flexible way.
