Dear all,
Recently, I have read the book <<Understanding the Linux Kernel>>
And I have two points not clearly about scheduler, hope someone here can
help me. Thank you in advance.
1. At book, there are below formula:
base time quantum = (140-static priority)*20 if static priority < 120
(140-static priority)*20 if static priority >=120
it is for i386/686, and this value should be HZ related. But I can't
find related code at sched.c, can anyone point it to me?
2. For the preemptive kernel, I know below situation may will happen
preempt implicitly(if i am error, please point out), are there any
situation will happen preempt?
1. The situation for each timer interrupt occurs:
i: If process time quantum expires, it will be replaced
ii: If process A(who owns CPU)'s priority is lower than process
B who is also at running queue. The process A will be replaced for
process B.
2. At IRQ handler, it wakes up process B. then, after IRQ exiting, the
higher priority process B will preempt process A who is interrupted by
above IRQ.
--
Best Regards
Peter Chen
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