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static unsigned long shrink_list(enum lru_list lru, unsigned long nr_to_scan, struct lruvec *lruvec, struct scan_control *sc) { if (is_active_lru(lru)) {

if (inactive_list_is_low(lruvec, is_file_lru(lru))) shrink_active_list(nr_to_scan, lruvec, sc, lru); return 0; } return shrink_inactive_list(nr_to_scan, lruvec, sc, lru);

}

static inline int is_active_lru(enum lru_list lru)

{ return (lru == LRU_ACTIVE_ANON || lru == LRU_ACTIVE_FILE); }

/*

 * The inactive anon list should be small enough that the VM never has  * to do too much work.  *  * The inactive file list should be small enough to leave most memory  * to the established workingset on the scan-resistant active list,  * but large enough to avoid thrashing the aggregate readahead window.  *  * Both inactive lists should also be large enough that each inactive  * page has a chance to be referenced again before it is reclaimed.  *  * The inactive_ratio is the target ratio of ACTIVE to INACTIVE pages  * on this LRU, maintained by the pageout code. A zone->inactive_ratio  * of 3 means 3:1 or 25% of the pages are kept on the inactive list.  *  * total     target    max  * memory    ratio     inactive  * -------------------------------------  *   10MB       1         5MB  *  100MB       1        50MB  *    1GB       3       250MB  *   10GB      10       0.9GB  *  100GB      31         3GB  *    1TB     101        10GB  *   10TB     320        32GB  */ static bool inactive_list_is_low(struct lruvec *lruvec, bool file) { unsigned long inactive_ratio; unsigned long inactive; unsigned long active; unsigned long gb; /* * If we don't have swap space, anonymous page deactivation * is pointless. */ if (!file && !total_swap_pages) return false; inactive = lruvec_lru_size(lruvec, file * LRU_FILE);

active = lruvec_lru_size(lruvec, file * LRU_FILE + LRU_ACTIVE);

gb = (inactive + active) >> (30 - PAGE_SHIFT);

if (gb)

inactive_ratio = int_sqrt(10 * gb);

else

inactive_ratio = 1;

return inactive * inactive_ratio < active; }

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