Linux kernel source scenario analysis-memory management recovery mapping

Refill_inactive_scan and Swap_out, turn active pages into inactive, dirty pages. The principle of selection is not recently accessed, and age is less than 0.

Page_launder, the inactive dirty page becomes inactive Clean page.

Inactive Dirty pages, have the following features:

The usage count is 1;

Page->list chain into mapping->dirty_pages/clean_pages;

Page->next_hash and Page->pprev_hash chain into the global hash table;

PAGE->LRU chain into the global inactive_dirty_list;

The page->flags corresponds to set to Pg_dirty.

Inactive Clean pages, have the following features:

The usage count is 1;

Page->list chain into mapping->dirty_pages/clean_pages (keep it as is);

Page->next_hash and Page->pprev_hash chain into the global hash table;

PAGE->LRU chain into the page->zone->inactive_clean_list;.

If a page break is interrupted and you visit this webpage again, the Lookup_swap_cache will be called, the corresponding page will be found in the global hash table, and the reference count plus 1 to 2, but not yet moved to the active queue . When do you move to the active queue ?

The answers are in, Page_launder and Reclaim_page.

Page_launder:

if (pagetestandclearreferenced (page) | | | page->age > 0 | |   At this point the reference count is greater than 1                 (!page->buffers && page_count (page) > 1) | |                  Page_ramdisk (page)) {              del_page_from_inactive_dirty_list (page);              Add_page_to_active_list (page);              Continue  

    

Reclaim_page:

if (pagetestandclearreferenced (page) | | | page->age > 0 | |                  (!page->buffers && Page_count (page) > 1)) {//At this time the reference count is greater than 1            del_page_from_inactive_clean_list (page);              Add_page_to_active_list (page);              Continue;  }  

Linux kernel source scenario analysis-memory management recovery mapping