The A/D bits exist entirely for the operating system's benefit. The Accessed bit tells the OS which pages have been recently used, enabling page replacement algorithms to choose pages to evict when memory runs low. The Dirty bit tells the OS which pages have been modified and must be written back to disk before eviction; clean pages can simply be discarded and re-read from disk later.
怎样创造政绩？关键靠实干，这是最质朴的方法论，是成就事业的必由之路。
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Зарина Дзагоева。关于这个话题，51吃瓜提供了深入分析
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