linux-kernel - Re: [PATCHv3 2/2] staging: ion: debugfs to shrink pool

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Message-ID: <559581D0.9070308@redhat.com>
Date:	Thu, 2 Jul 2015 11:24:16 -0700
From:	Laura Abbott <labbott@...hat.com>
To:	Gioh Kim <gioh.kim@....com>, gregkh@...uxfoundation.org,
	arve@...roid.com, riandrews@...roid.com,
	devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCHv3 2/2] staging: ion: debugfs to shrink pool

On 07/01/2015 04:02 AM, Gioh Kim wrote:
> This patch enables debugfs file /sys/kernel/debug/ion/heaps/system_shrink

Nit: This technically enables debugfs shrinking for all heaps, not just
the system heap although the system heap is the only one with a shrinker
right now.

> to shrink pool and get pool size. It is already implemented
> but not complete. This patch completes and enables it.
>
> Reading the file returns pool size
> in page unit and writing the number of pages shrinks pool.
> It flushes all pages to write zero at the file.
>
> Signed-off-by: Gioh Kim <gioh.kim@....com>

Reviewed-by: Laura Abbott <labbott@...hat.com>

> ---
>   drivers/staging/android/ion/ion.c |   22 +++++++++-------------
>   1 file changed, 9 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/staging/android/ion/ion.c b/drivers/staging/android/ion/ion.c
> index 6f48112..9327e8a 100644
> --- a/drivers/staging/android/ion/ion.c
> +++ b/drivers/staging/android/ion/ion.c
> @@ -1466,7 +1466,6 @@ 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;
> @@ -1474,15 +1473,14 @@ static int debug_shrink_set(void *data, u64 val)
>   	int objs;
>
>   	sc.gfp_mask = -1;
> -	sc.nr_to_scan = 0;
> -
> -	if (!val)
> -		return 0;
> +	sc.nr_to_scan = val;
>
> -	objs = heap->shrinker.shrink(&heap->shrinker, &sc);
> -	sc.nr_to_scan = objs;
> +	if (!val) {
> +		objs = heap->shrinker.count_objects(&heap->shrinker, &sc);
> +		sc.nr_to_scan = objs;
> +	}
>
> -	heap->shrinker.shrink(&heap->shrinker, &sc);
> +	heap->shrinker.scan_objects(&heap->shrinker, &sc);
>   	return 0;
>   }
>
> @@ -1495,14 +1493,13 @@ static int debug_shrink_get(void *data, u64 *val)
>   	sc.gfp_mask = -1;
>   	sc.nr_to_scan = 0;
>
> -	objs = heap->shrinker.shrink(&heap->shrinker, &sc);
> +	objs = heap->shrinker.count_objects(&heap->shrinker, &sc);
>   	*val = objs;
>   	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)
>   {
> @@ -1540,8 +1537,7 @@ 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->shrinker.count_objects && heap->shrinker.scan_objects) {
>   		char debug_name[64];
>
>   		snprintf(debug_name, 64, "%s_shrink", heap->name);
> @@ -1556,7 +1552,7 @@ void ion_device_add_heap(struct ion_device *dev, struct ion_heap *heap)
>   				path, debug_name);
>   		}
>   	}
> -#endif
> +
>   	up_write(&dev->lock);
>   }
>
>

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