Re: [PATCH] vmscan: page_check_references() check low order lumpy reclaim properly

[KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>]

> > @@ -77,6 +77,8 @@ struct scan_control {
> >  
> >  	int order;
> >  
> > +	int lumpy_reclaim;
> > +
> 
> Needs a comment explaining its role, please.  Something like "direct
> this reclaim run to perform lumpy reclaim"?
> 
> A clearer name might be "lumpy_relcaim_mode"?
> 
> Making it a `bool' would clarify things too.

Sorry, I've missed your this review comment.
How about this?


---
 mm/vmscan.c |   39 ++++++++++++++++++++++++---------------
 1 files changed, 24 insertions(+), 15 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 13d9546..c3bcdd4 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -77,7 +77,11 @@ struct scan_control {
 
 	int order;
 
-	int lumpy_reclaim;
+	/*
+	 * Intend to reclaim enough contenious memory rather than to reclaim
+	 * enough amount memory. I.e, it's the mode for high order allocation.
+	 */
+	bool lumpy_reclaim_mode;
 
 	/* Which cgroup do we reclaim from */
 	struct mem_cgroup *mem_cgroup;
@@ -577,7 +581,7 @@ static enum page_references page_check_references(struct page *page,
 	referenced_page = TestClearPageReferenced(page);
 
 	/* Lumpy reclaim - ignore references */
-	if (sc->lumpy_reclaim)
+	if (sc->lumpy_reclaim_mode)
 		return PAGEREF_RECLAIM;
 
 	/*
@@ -1153,7 +1157,7 @@ static unsigned long shrink_inactive_list(unsigned long max_scan,
 		unsigned long nr_freed;
 		unsigned long nr_active;
 		unsigned int count[NR_LRU_LISTS] = { 0, };
-		int mode = sc->lumpy_reclaim ? ISOLATE_BOTH : ISOLATE_INACTIVE;
+		int mode = sc->lumpy_reclaim_mode ? ISOLATE_BOTH : ISOLATE_INACTIVE;
 		unsigned long nr_anon;
 		unsigned long nr_file;
 
@@ -1206,7 +1210,7 @@ static unsigned long shrink_inactive_list(unsigned long max_scan,
 		 * but that should be acceptable to the caller
 		 */
 		if (nr_freed < nr_taken && !current_is_kswapd() &&
-		    sc->lumpy_reclaim) {
+		    sc->lumpy_reclaim_mode) {
 			congestion_wait(BLK_RW_ASYNC, HZ/10);
 
 			/*
@@ -1609,6 +1613,21 @@ static unsigned long nr_scan_try_batch(unsigned long nr_to_scan,
 	return nr;
 }
 
+static void set_lumpy_reclaim_mode(int priority, struct scan_control *sc)
+{
+	/*
+	 * If we need a large contiguous chunk of memory, or have
+	 * trouble getting a small set of contiguous pages, we
+	 * will reclaim both active and inactive pages.
+	 */
+	if (sc->order > PAGE_ALLOC_COSTLY_ORDER)
+		sc->lumpy_reclaim_mode = 1;
+	else if (sc->order && priority < DEF_PRIORITY - 2)
+		sc->lumpy_reclaim_mode = 1;
+	else
+		sc->lumpy_reclaim_mode = 0;
+}
+
 /*
  * This is a basic per-zone page freer.  Used by both kswapd and direct reclaim.
  */
@@ -1645,17 +1664,7 @@ static void shrink_zone(int priority, struct zone *zone,
 					  &reclaim_stat->nr_saved_scan[l]);
 	}
 
-	/*
-	 * If we need a large contiguous chunk of memory, or have
-	 * trouble getting a small set of contiguous pages, we
-	 * will reclaim both active and inactive pages.
-	 */
-	if (sc->order > PAGE_ALLOC_COSTLY_ORDER)
-		sc->lumpy_reclaim = 1;
-	else if (sc->order && priority < DEF_PRIORITY - 2)
-		sc->lumpy_reclaim = 1;
-	else
-		sc->lumpy_reclaim = 0;
+	set_lumpy_reclaim_mode(priority, sc);
 
 	while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] ||
 					nr[LRU_INACTIVE_FILE]) {
-- 
1.6.5.2





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