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2005-07-25

Repaging in AIX VM


Repaging“ was mentioned to me by Rik van Riel long time ago. How this can be implemented in Linux? E.g., add ->repage_tree radix-tree to struct address_space. (We get 32 bits per-page this way, while we need only one!) Insert entry into this tree on each page fault. Do _not_ remove entry when page is reclaimed. As a result, ->repage_tree keeps history of page faults. Check it on page fault. If there is an entry for page being faulted in---we have „repage“. Maintain global counter of elements in ->repage_tree's. When it's higher than some threshold (AIX uses total number of frames in the primary storage), start removing ->repage_tree elements on reclaim. Disadvantage: history is lost when struct address_space is destroyed.

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