推 genioushebe:我也看不大懂...@@ 01/12 00:46
※ 引述《genioushebe (我是路人...)》之銘言：
: 8.7 為什麼有時候會把分段跟分頁合在一起用
: 分段分頁(Segmented paging)在page table很大的時候很有用，在page table中一個沒有
: 用到的大塊連續段落可以塞到一個page table address為0的segment table中。當一個
: segment很大的時候，需要很多時間來allocation，則可以用分頁分段(Paged
: segmentation)處理這種情況。而靠著分頁分段(paging the segments)可以減少因為外部
: 斷裂引起的記憶體浪費及簡化allocation。
Segmentation and paging are often combined in order to improve upon each other.
Segmented paging is helpful when the page table becomes very large. A large
contiguous section of the page table that is unused can be collapsed into a
single segment table entry with a page-table address of zero.
Paged segmentation handles the case of having very long segments that require
a lot of time for allocation. By paging the segments, we reduce wasted memory
due to external fragmentation as well as simplify the allocation.
: 8.8 為什麼分段比分頁容易共用可重進入的模組
: 因為分段是邏輯記憶體的分割而不是實體記憶體，所以不論任何大小的分段都可以跟
: segment table中的entry共用，分頁必須在每個page的page table中有共同的entry才能
: 達到共享。
Since segmentation is based on a logical division of memory rather than a
physical one, segments of any size can be shared with only one entry in the
segment tables of each user. With paging there must be a common entry in the
page tables for each page that is shared.
附上原文
我自己也看不太懂我在翻什麼....
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