Re: [RFCv2 3/3] staging: ion: limit pool size

[Laura Abbott]

Hi,

On 10/23/2014 11:47 PM, Gioh Kim wrote:
> This patch limits pool size by page unit.

This looks useful. Might be nice to add a debugfs option
to change this at runtime as well.

> Signed-off-by: Gioh Kim <gioh.kim@xxxxxxx>
> ---
>   drivers/staging/android/ion/Kconfig         |    4 ++++
>   drivers/staging/android/ion/ion_page_pool.c |   26 ++++++++++++++++----------
>   2 files changed, 20 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/staging/android/ion/Kconfig b/drivers/staging/android/ion/Kconfig
> index 3452346..e6b1a54 100644
> --- a/drivers/staging/android/ion/Kconfig
> +++ b/drivers/staging/android/ion/Kconfig
> @@ -33,3 +33,7 @@ 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"

Can you add help text here? It would be useful to clarify that the
units are in pages and that 0 will allow unlimited growth of the
pool. This should also clarify that this is a limit per
individual pool and not a limit for all page pools in the system.

> diff --git a/drivers/staging/android/ion/ion_page_pool.c b/drivers/staging/android/ion/ion_page_pool.c
> index 165152f..d63e93f 100644
> --- a/drivers/staging/android/ion/ion_page_pool.c
> +++ b/drivers/staging/android/ion/ion_page_pool.c
> @@ -22,8 +22,11 @@
>   #include <linux/module.h>
>   #include <linux/slab.h>
>   #include <linux/swap.h>
> +#include <linux/kconfig.h>
>   #include "ion_priv.h"
>
> +#define POOL_LIMIT CONFIG_ION_POOL_LIMIT
> +

I don't think the extra #define helps anything here, was
there something else intended here?

>   static void *ion_page_pool_alloc_pages(struct ion_page_pool *pool)
>   {
>   	struct page *page = alloc_pages(pool->gfp_mask, pool->order);
> @@ -41,8 +44,21 @@ 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 (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 +119,6 @@ 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)
>   {

Thanks,
Laura

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