[PATCH 0/3] enable pool shrinking in page unit

[PATCH 0/3] enable pool shrinking in page unit

[Gioh Kim]

Hello,

Current shrinking is not page unit, block unit.
But shrinker returns the pool size in page unit,
so it is confused.

And there is no way to control pool size and shrink pool directly.

I have 3 patches:

1. Patch 1/3: make pool be shrinked by page unit
This patch trys to shrink pool in page unit.

2. Patch 2/3: enable debugfs to shrink page directly
This patch enables debugfs to specify shrink amount.

3. Patch 3/3: limit pool size
This patch specifies pool size limit.

This patchset is based on linux-next-20141023.

Gioh Kim (3):
  staging: ion: shrink page-pool by page unit
  staging: ion: debugfs to shrink pool
  staging: ion: limit pool size

 drivers/staging/android/ion/Kconfig           |    8 +++++++
 drivers/staging/android/ion/ion.c             |   31 +++++++------------------
 drivers/staging/android/ion/ion_page_pool.c   |   29 +++++++++++++----------
 drivers/staging/android/ion/ion_system_heap.c |    7 ++++--
 4 files changed, 38 insertions(+), 37 deletions(-)

-- 
1.7.9.5

[PATCH 1/3] staging: ion: shrink page-pool by page unit

[Gioh Kim]

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.

Signed-off-by: Gioh Kim <gioh.kim@lge.com>
---
 drivers/staging/android/ion/ion_page_pool.c   |    5 +++--
 drivers/staging/android/ion/ion_system_heap.c |    7 +++++--
 2 files changed, 8 insertions(+), 4 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..91d862f 100644
--- a/drivers/staging/android/ion/ion_system_heap.c
+++ b/drivers/staging/android/ion/ion_system_heap.c
@@ -211,7 +211,7 @@ static int ion_system_heap_shrink(struct ion_heap *heap, gfp_t gfp_mask,
 					int nr_to_scan)
 {
 	struct ion_system_heap *sys_heap;
-	int nr_total = 0;
+	int nr_total = 0, nr_freed;
 	int i;
 
 	sys_heap = container_of(heap, struct ion_system_heap, heap);
@@ -219,7 +219,10 @@ static int ion_system_heap_shrink(struct ion_heap *heap, gfp_t gfp_mask,
 	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;
+		/* nr_to_scan can be negative */
+		nr_to_scan -= nr_freed;
 	}
 
 	return nr_total;
-- 
1.7.9.5

Re: [PATCH 1/3] staging: ion: shrink page-pool by page unit

[Gioh Kim]

2014-10-28 오전 9:36에 Gioh Kim 이(가) 쓴 글:
> 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.
> 
> Signed-off-by: Gioh Kim <gioh.kim@lge.com>
> ---
>   drivers/staging/android/ion/ion_page_pool.c   |    5 +++--
>   drivers/staging/android/ion/ion_system_heap.c |    7 +++++--
>   2 files changed, 8 insertions(+), 4 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..91d862f 100644
> --- a/drivers/staging/android/ion/ion_system_heap.c
> +++ b/drivers/staging/android/ion/ion_system_heap.c
> @@ -211,7 +211,7 @@ static int ion_system_heap_shrink(struct ion_heap *heap, gfp_t gfp_mask,
>   					int nr_to_scan)
>   {
>   	struct ion_system_heap *sys_heap;
> -	int nr_total = 0;
> +	int nr_total = 0, nr_freed;
>   	int i;
>   
>   	sys_heap = container_of(heap, struct ion_system_heap, heap);
> @@ -219,7 +219,10 @@ static int ion_system_heap_shrink(struct ion_heap *heap, gfp_t gfp_mask,
>   	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);

I found a mistake that if nr_to_scan is 0, this works wrong.
Please ignore this patch and I'm going to send v2.


> +		nr_total += nr_freed;
> +		/* nr_to_scan can be negative */
> +		nr_to_scan -= nr_freed;
>   	}
>   
>   	return nr_total;
> 

[PATCH 2/3] staging: ion: debugfs to shrink pool

[Gioh Kim]

This patch enables debugfs files /sys/kernel/debug/ion/heaps/system_shrink
,which was commented out, to shrink pool or get pool size
Reading the file returns pool size and writing occurs to shrink pool.

Signed-off-by: Gioh Kim <gioh.kim@lge.com>
---
 drivers/staging/android/ion/ion.c |   31 ++++++++-----------------------
 1 file changed, 8 insertions(+), 23 deletions(-)

diff --git a/drivers/staging/android/ion/ion.c b/drivers/staging/android/ion/ion.c
index 290d4d2..ecc1121 100644
--- a/drivers/staging/android/ion/ion.c
+++ b/drivers/staging/android/ion/ion.c
@@ -1463,43 +1463,29 @@ static const struct file_operations debug_heap_fops = {
 	.release = single_release,
 };
 
-#ifdef DEBUG_HEAP_SHRINKER
 static int debug_shrink_set(void *data, u64 val)
 {
 	struct ion_heap *heap = data;
-	struct shrink_control sc;
 	int objs;
 
-	sc.gfp_mask = -1;
-	sc.nr_to_scan = 0;
-
-	if (!val)
-		return 0;
-
-	objs = heap->shrinker.shrink(&heap->shrinker, &sc);
-	sc.nr_to_scan = objs;
+	if (val)
+		objs = val;
+	else
+		objs = heap->ops->shrink(heap, __GFP_HIGHMEM, 0);
 
-	heap->shrinker.shrink(&heap->shrinker, &sc);
+	(void)heap->ops->shrink(heap, __GFP_HIGHMEM, objs);
 	return 0;
 }
 
 static int debug_shrink_get(void *data, u64 *val)
 {
 	struct ion_heap *heap = data;
-	struct shrink_control sc;
-	int objs;
-
-	sc.gfp_mask = -1;
-	sc.nr_to_scan = 0;
-
-	objs = heap->shrinker.shrink(&heap->shrinker, &sc);
-	*val = objs;
+	*val = heap->ops->shrink(heap, __GFP_HIGHMEM, 0);
 	return 0;
 }
 
 DEFINE_SIMPLE_ATTRIBUTE(debug_shrink_fops, debug_shrink_get,
 			debug_shrink_set, "%llu\n");
-#endif
 
 void ion_device_add_heap(struct ion_device *dev, struct ion_heap *heap)
 {
@@ -1534,8 +1520,7 @@ void ion_device_add_heap(struct ion_device *dev, struct ion_heap *heap)
 			path, heap->name);
 	}
 
-#ifdef DEBUG_HEAP_SHRINKER
-	if (heap->shrinker.shrink) {
+	if (heap->ops->shrink) {
 		char debug_name[64];
 
 		snprintf(debug_name, 64, "%s_shrink", heap->name);
@@ -1550,7 +1535,7 @@ void ion_device_add_heap(struct ion_device *dev, struct ion_heap *heap)
 				path, debug_name);
 		}
 	}
-#endif
+
 	up_write(&dev->lock);
 }
 
-- 
1.7.9.5

[PATCH 3/3] staging: ion: limit pool size

[Gioh Kim]

This patch limits pool size by page unit.

Signed-off-by: Gioh Kim <gioh.kim@lge.com>
---
 drivers/staging/android/ion/Kconfig         |    8 ++++++++
 drivers/staging/android/ion/ion_page_pool.c |   24 ++++++++++++++----------
 2 files changed, 22 insertions(+), 10 deletions(-)

diff --git a/drivers/staging/android/ion/Kconfig b/drivers/staging/android/ion/Kconfig
index 3452346..06b4466 100644
--- a/drivers/staging/android/ion/Kconfig
+++ b/drivers/staging/android/ion/Kconfig
@@ -33,3 +33,11 @@ config ION_TEGRA
 	help
 	  Choose this option if you wish to use ion on an nVidia Tegra.
 
+config ION_POOL_LIMIT
+	int "Limit count of pages in pool"
+	depends on ION
+	default "0"
+	help
+	  Set the maximum number of pages the individual pool can have.
+	  This doesn't care the total pages of all pools.
+	  0 means no limit.
diff --git a/drivers/staging/android/ion/ion_page_pool.c b/drivers/staging/android/ion/ion_page_pool.c
index 165152f..15d1ac8 100644
--- a/drivers/staging/android/ion/ion_page_pool.c
+++ b/drivers/staging/android/ion/ion_page_pool.c
@@ -22,6 +22,7 @@
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/swap.h>
+#include <linux/kconfig.h>
 #include "ion_priv.h"
 
 static void *ion_page_pool_alloc_pages(struct ion_page_pool *pool)
@@ -41,8 +42,21 @@ static void ion_page_pool_free_pages(struct ion_page_pool *pool,
 	__free_pages(page, pool->order);
 }
 
+static int ion_page_pool_total(struct ion_page_pool *pool, bool high)
+{
+	int count = pool->low_count;
+
+	if (high)
+		count += pool->high_count;
+
+	return count << pool->order;
+}
+
 static int ion_page_pool_add(struct ion_page_pool *pool, struct page *page)
 {
+	if (CONFIG_ION_POOL_LIMIT && ion_page_pool_total(pool, 1) > POOL_LIMIT)
+		return 1;
+
 	mutex_lock(&pool->mutex);
 	if (PageHighMem(page)) {
 		list_add_tail(&page->lru, &pool->high_items);
@@ -103,16 +117,6 @@ void ion_page_pool_free(struct ion_page_pool *pool, struct page *page)
 		ion_page_pool_free_pages(pool, page);
 }
 
-static int ion_page_pool_total(struct ion_page_pool *pool, bool high)
-{
-	int count = pool->low_count;
-
-	if (high)
-		count += pool->high_count;
-
-	return count << pool->order;
-}
-
 int ion_page_pool_shrink(struct ion_page_pool *pool, gfp_t gfp_mask,
 				int nr_to_scan)
 {
-- 
1.7.9.5