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

From: Gioh Kim
Date: Sun Oct 26 2014 - 20:48:54 EST




2014-10-25 ìì 5:53, Laura Abbott ì ê:
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?

No, I just follow other codes.
If it isn't necessary, I will remove it at v2 patch.



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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