NS_MAX_SLEEP_AVG; JIFFIES_TO_NS; MAX_SLEEP_AVG

纳秒级最长睡眠时间为1000 000 000ns
NS_MAX_SLEEP_AVG = 1000 * 1000 000 = 1000 000 000ns
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#define NS_MAX_SLEEP_AVG    (JIFFIES_TO_NS(MAX_SLEEP_AVG))

将TIME个滴答转化为纳秒(ns)
TIME * 1ms = TIME * 1000 000ns
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#define JIFFIES_TO_NS(TIME) ((TIME) * (1000000000 / HZ))

最长睡眠时间为1000ms(1s)
MAX_SLEEP_AVG = 100 * 10 = 1000ms = 1000ticks
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#define MAX_SLEEP_AVG       (DEF_TIMESLICE * MAX_BONUS)