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/* * Determine how aggressively the anon and file LRU lists should be * scanned. The relative value of each set of LRU lists is determined * by looking at the fraction of the pages scanned we did rotate back * onto the active list instead of evict. * * nr[0] = anon inactive pages to scan; nr[1] = anon active pages to scan * nr[2] = file inactive pages to scan; nr[3] = file active pages to scan */ static void get_scan_count(struct lruvec *lruvec, struct mem_cgroup *memcg, struct scan_control *sc, unsigned long *nr, unsigned long *lru_pages) { int swappiness = mem_cgroup_swappiness(memcg); struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat; u64 fraction[2]; u64 denominator = 0; /* gcc */ struct zone *zone = lruvec_zone(lruvec); unsigned long anon_prio, file_prio; enum scan_balance scan_balance; unsigned long anon, file; bool force_scan = false; unsigned long ap, fp; enum lru_list lru; bool some_scanned; int pass; if (current_is_kswapd()) { if (!zone_reclaimable(zone)) force_scan = true; if (!mem_cgroup_online(memcg)) force_scan = true; } if (!global_reclaim(sc)) force_scan = true; /* If we have no swap space, do not bother scanning anon pages. */ if (!sc->may_swap || mem_cgroup_get_nr_swap_pages(memcg) <= 0) { scan_balance = SCAN_FILE; goto out; } if (!global_reclaim(sc) && !swappiness) { scan_balance = SCAN_FILE; goto out; } if (!sc->priority && swappiness) { scan_balance = SCAN_EQUAL; goto out; } if (global_reclaim(sc)) { unsigned long zonefile; unsigned long zonefree;zonefree = zone_page_state(zone, NR_FREE_PAGES);
zonefile = zone_page_state(zone, NR_ACTIVE_FILE) + zone_page_state(zone, NR_INACTIVE_FILE); if (unlikely(zonefile + zonefree <= high_wmark_pages(zone))) { scan_balance = SCAN_ANON; goto out; } } if (!inactive_list_is_low(lruvec, true) && lruvec_lru_size(lruvec, LRU_INACTIVE_FILE) >> sc->priority) { scan_balance = SCAN_FILE; goto out; } scan_balance = SCAN_FRACT; anon_prio = swappiness; file_prio = 200 - anon_prio; anon = lruvec_lru_size(lruvec, LRU_ACTIVE_ANON) + lruvec_lru_size(lruvec, LRU_INACTIVE_ANON); file = lruvec_lru_size(lruvec, LRU_ACTIVE_FILE) + lruvec_lru_size(lruvec, LRU_INACTIVE_FILE); spin_lock_irq(&zone->lru_lock); if (unlikely(reclaim_stat->recent_scanned[0] > anon / 4)) { reclaim_stat->recent_scanned[0] /= 2; reclaim_stat->recent_rotated[0] /= 2; } if (unlikely(reclaim_stat->recent_scanned[1] > file / 4)) { reclaim_stat->recent_scanned[1] /= 2; reclaim_stat->recent_rotated[1] /= 2; } ap = anon_prio * (reclaim_stat->recent_scanned[0] + 1); ap /= reclaim_stat->recent_rotated[0] + 1; fp = file_prio * (reclaim_stat->recent_scanned[1] + 1); fp /= reclaim_stat->recent_rotated[1] + 1; spin_unlock_irq(&zone->lru_lock); fraction[0] = ap; fraction[1] = fp; denominator = ap + fp + 1; out: some_scanned = false; /* Only use force_scan on second pass. */ for (pass = 0; !some_scanned && pass < 2; pass++) { *lru_pages = 0; for_each_evictable_lru(lru) { int file = is_file_lru(lru); unsigned long size; unsigned long scan; size = lruvec_lru_size(lruvec, lru); scan = size >> sc->priority; if (!scan && pass && force_scan) scan = min(size, SWAP_CLUSTER_MAX); switch (scan_balance) { case SCAN_EQUAL: /* Scan lists relative to size */ break; case SCAN_FRACT: scan = div64_u64(scan * fraction[file],denominator); break; case SCAN_FILE: case SCAN_ANON: /* Scan one type exclusively */ if ((scan_balance == SCAN_FILE) != file) { size = 0; scan = 0; } break; default: /* Look ma, no brain */ BUG(); } *lru_pages += size; nr[lru] = scan; /* * Skip the second pass and don't force_scan,if we found something to scan. */ some_scanned |= !!scan; } } }转载地址：http://lxqti.baihongyu.com/