Hello Minchan,
First of all, I agree with the overall purpose of your patch set.
On 09/04/2014 10:39 AM, Minchan Kim wrote:
This patch implement SWAP_GET_FREE handler in zram so that VM can
know how many zram has freeable space.
VM can use it to stop anonymous reclaiming once zram is full.
Signed-off-by: Minchan Kim <minc...@kernel.org>
---
drivers/block/zram/zram_drv.c | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 88661d62e46a..8e22b20aa2db 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -951,6 +951,22 @@ static int zram_slot_free_notify(struct block_device *bdev,
return 0;
}
+static int zram_get_free_pages(struct block_device *bdev, long *free)
+{
+ struct zram *zram;
+ struct zram_meta *meta;
+
+ zram = bdev->bd_disk->private_data;
+ meta = zram->meta;
+
+ if (!zram->limit_pages)
+ return 1;
+
+ *free = zram->limit_pages - zs_get_total_pages(meta->mem_pool);
Even if 'free' is zero here, there may be free spaces available to store
more compressed pages into the zs_pool. I mean calculation above is not
quite accurate and wastes memory, but have no better idea for now.
heesub
+
+ return 0;
+}
+
static int zram_swap_hint(struct block_device *bdev,
unsigned int hint, void *arg)
{
@@ -958,6 +974,8 @@ static int zram_swap_hint(struct block_device *bdev,
if (hint == SWAP_SLOT_FREE)
ret = zram_slot_free_notify(bdev, (unsigned long)arg);
+ else if (hint == SWAP_GET_FREE)
+ ret = zram_get_free_pages(bdev, arg);
return ret;
}
--
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