linux-kernel - [PATCHv2 1/3] staging: ion: shrink page-pool by page unit

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Date:	Wed, 29 Oct 2014 14:35:58 +0900
From:	Gioh Kim <gioh.kim@....com>
To:	gregkh@...uxfoundation.org, john.stultz@...aro.org,
	rebecca@...roid.com, lauraa@...eaurora.org,
	dan.carpenter@...cle.com, minchan@...nel.org,
	iamjoonsoo.kim@....com
Cc:	devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org,
	gunho.lee@....com, Gioh Kim <gioh.kim@....com>
Subject: [PATCHv2 1/3] staging: ion: shrink page-pool by page unit

This patch shrink page-pool by page unit.

Shrinker usually get the pool size with the pool-scanner
and pass the size to the pool-counter to shrink entire pool.
But the pool-scanner is working in block unit.
and pool-counter page unit.
So it is confused.

Change-Id: If25c693c09f6ebd14c87809feddb72f9058e8308
Signed-off-by: Gioh Kim <gioh.kim@....com>
---
 drivers/staging/android/ion/ion_page_pool.c   |    5 +++--
 drivers/staging/android/ion/ion_system_heap.c |   18 +++++++++++++++---
 2 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/drivers/staging/android/ion/ion_page_pool.c b/drivers/staging/android/ion/ion_page_pool.c
index 5864f3d..165152f 100644
--- a/drivers/staging/android/ion/ion_page_pool.c
+++ b/drivers/staging/android/ion/ion_page_pool.c
@@ -116,7 +116,7 @@ static int ion_page_pool_total(struct ion_page_pool *pool, bool high)
 int ion_page_pool_shrink(struct ion_page_pool *pool, gfp_t gfp_mask,
 				int nr_to_scan)
 {
-	int freed;
+	int freed = 0;
 	bool high;
 
 	if (current_is_kswapd())
@@ -127,7 +127,7 @@ int ion_page_pool_shrink(struct ion_page_pool *pool, gfp_t gfp_mask,
 	if (nr_to_scan == 0)
 		return ion_page_pool_total(pool, high);
 
-	for (freed = 0; freed < nr_to_scan; freed++) {
+	while (freed <= nr_to_scan) {
 		struct page *page;
 
 		mutex_lock(&pool->mutex);
@@ -141,6 +141,7 @@ int ion_page_pool_shrink(struct ion_page_pool *pool, gfp_t gfp_mask,
 		}
 		mutex_unlock(&pool->mutex);
 		ion_page_pool_free_pages(pool, page);
+		freed += (1 << pool->order);
 	}
 
 	return freed;
diff --git a/drivers/staging/android/ion/ion_system_heap.c b/drivers/staging/android/ion/ion_system_heap.c
index da2a63c..0ba8aaf 100644
--- a/drivers/staging/android/ion/ion_system_heap.c
+++ b/drivers/staging/android/ion/ion_system_heap.c
@@ -29,7 +29,7 @@
 static gfp_t high_order_gfp_flags = (GFP_HIGHUSER | __GFP_ZERO | __GFP_NOWARN |
 				     __GFP_NORETRY) & ~__GFP_WAIT;
 static gfp_t low_order_gfp_flags  = (GFP_HIGHUSER | __GFP_ZERO | __GFP_NOWARN);
-static const unsigned int orders[] = {8, 4, 0};
+static const unsigned int orders[] = {8, 6, 4, 0};
 static const int num_orders = ARRAY_SIZE(orders);
 static int order_to_index(unsigned int order)
 {
@@ -212,14 +212,26 @@ static int ion_system_heap_shrink(struct ion_heap *heap, gfp_t gfp_mask,
 {
 	struct ion_system_heap *sys_heap;
 	int nr_total = 0;
-	int i;
+	int i, nr_freed;
+	int only_scan = 0;
 
 	sys_heap = container_of(heap, struct ion_system_heap, heap);
 
+	if (!nr_to_scan)
+		only_scan = 1;
+
 	for (i = 0; i < num_orders; i++) {
 		struct ion_page_pool *pool = sys_heap->pools[i];
 
-		nr_total += ion_page_pool_shrink(pool, gfp_mask, nr_to_scan);
+		nr_freed = ion_page_pool_shrink(pool, gfp_mask, nr_to_scan);
+		nr_total += nr_freed;
+
+		if (!only_scan) {
+			nr_to_scan -= nr_freed;
+			/* shrink completed */
+			if (nr_to_scan <= 0)
+				break;
+		}
 	}
 
 	return nr_total;
-- 
1.7.9.5

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