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Commit 2903fb16 authored by Christoph Lameter's avatar Christoph Lameter Committed by Linus Torvalds
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[PATCH] vmscan: skip reclaim_mapped determination if we do not swap 



This puts the variables and the way to get to reclaim_mapped in one block.
And allows zone_reclaim or other things to skip the determination (maybe
this whole block of code does not belong into refill_inactive_zone()?)

Signed-off-by: default avatarChristoph Lameter <clameter@sgi.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 072eaa5d

mm/vmscan.c

+41 −34
Original line number Diff line number Diff line
@@ -1195,48 +1195,55 @@ refill_inactive_zone(struct zone *zone, struct scan_control *sc) 
	struct page *page;

	struct pagevec pvec;

	int reclaim_mapped = 0;



	if (unlikely(sc->may_swap)) {

		long mapped_ratio;

		long distress;

		long swap_tendency;



	lru_add_drain();

	spin_lock_irq(&zone->lru_lock);

	pgmoved = isolate_lru_pages(nr_pages, &zone->active_list,

				    &l_hold, &pgscanned);

	zone->pages_scanned += pgscanned;

	zone->nr_active -= pgmoved;

	spin_unlock_irq(&zone->lru_lock);



		/*

	 * `distress' is a measure of how much trouble we're having reclaiming

	 * pages.  0 -> no problems.  100 -> great trouble.

		 * `distress' is a measure of how much trouble we're having

		 * reclaiming pages.  0 -> no problems.  100 -> great trouble.

		 */

		distress = 100 >> zone->prev_priority;



		/*

	 * The point of this algorithm is to decide when to start reclaiming

	 * mapped memory instead of just pagecache.  Work out how much memory

		 * The point of this algorithm is to decide when to start

		 * reclaiming mapped memory instead of just pagecache.  Work out

		 * how much memory

		 * is mapped.

		 */

		mapped_ratio = (sc->nr_mapped * 100) / total_memory;



		/*

	 * Now decide how much we really want to unmap some pages.  The mapped

	 * ratio is downgraded - just because there's a lot of mapped memory

	 * doesn't necessarily mean that page reclaim isn't succeeding.

		 * Now decide how much we really want to unmap some pages.  The

		 * mapped ratio is downgraded - just because there's a lot of

		 * mapped memory doesn't necessarily mean that page reclaim

		 * isn't succeeding.

		 *

	 * The distress ratio is important - we don't want to start going oom.

		 * The distress ratio is important - we don't want to start

		 * going oom.

		 *

	 * A 100% value of vm_swappiness overrides this algorithm altogether.

		 * A 100% value of vm_swappiness overrides this algorithm

		 * altogether.

		 */

		swap_tendency = mapped_ratio / 2 + distress + vm_swappiness;



		/*

	 * Now use this metric to decide whether to start moving mapped memory

	 * onto the inactive list.

		 * Now use this metric to decide whether to start moving mapped

		 * memory onto the inactive list.

		 */

	if (swap_tendency >= 100 && sc->may_swap)

		if (swap_tendency >= 100)

			reclaim_mapped = 1;

	}



	lru_add_drain();

	spin_lock_irq(&zone->lru_lock);

	pgmoved = isolate_lru_pages(nr_pages, &zone->active_list,

				    &l_hold, &pgscanned);

	zone->pages_scanned += pgscanned;

	zone->nr_active -= pgmoved;

	spin_unlock_irq(&zone->lru_lock);



	while (!list_empty(&l_hold)) {

		cond_resched();