[PATCH v3 16/16] zram: use __GFP_MOVABLE for memory allocation

Minchan Kim
2016-03-30T07:12:34Z

Zsmalloc is ready for page migration so zram can use __GFP_MOVABLE
from now on.

I did test to see how it helps to make higher order pages.
Test scenario is as follows.

KVM guest, 1G memory, ext4 formated zram block device,

for i in `seq 1 8`;
do
dd if=/dev/vda1 of=mnt/test$i.txt bs=128M count=1 &
done

wait `pidof dd`

for i in `seq 1 2 8`;
do
rm -rf mnt/test$i.txt
done
fstrim -v mnt

echo "init"
cat /proc/buddyinfo

echo "compaction"
echo 1 > /proc/sys/vm/compact_memory
cat /proc/buddyinfo

old:

init
Node 0, zone DMA 208 120 51 41 11 0 0 0 0 0 0
Node 0, zone DMA32 16380 13777 9184 3805 789 54 3 0 0 0 0
compaction
Node 0, zone DMA 132 82 40 39 16 2 1 0 0 0 0
Node 0, zone DMA32 5219 5526 4969 3455 1831 677 139 15 0 0 0

new:

init
Node 0, zone DMA 379 115 97 19 2 0 0 0 0 0 0
Node 0, zone DMA32 18891 16774 10862 3947 637 21 0 0 0 0 0
compaction 1
Node 0, zone DMA 214 66 87 29 10 3 0 0 0 0 0
Node 0, zone DMA32 1612 3139 3154 2469 1745 990 384 94 7 0 0

As you can see, compaction made so many high-order pages. Yay!

Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Minchan Kim <minchan@kernel.org>
---
drivers/block/zram/zram_drv.c | 3 ++-
mm/zsmalloc.c | 2 +-
2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 370c2f76016d..10f6ff1cf6a0 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -514,7 +514,8 @@ static struct zram_meta *zram_meta_alloc(char *pool_name, u64 disksize)
goto out_error;
}

- meta->mem_pool = zs_create_pool(pool_name, GFP_NOIO | __GFP_HIGHMEM);
+ meta->mem_pool = zs_create_pool(pool_name, GFP_NOIO|__GFP_HIGHMEM
+ |__GFP_MOVABLE);
if (!meta->mem_pool) {
pr_err("Error creating memory pool\n");
goto out_error;
diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index e24f4a160892..4b1ccb68f2ee 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -308,7 +308,7 @@ static void destroy_handle_cache(struct zs_pool *pool)
static unsigned long alloc_handle(struct zs_pool *pool)
{
return (unsigned long)kmem_cache_alloc(pool->handle_cachep,
- pool->flags & ~__GFP_HIGHMEM);
+ pool->flags & ~(__GFP_HIGHMEM|__GFP_MOVABLE));
}

static void free_handle(struct zs_pool *pool, unsigned long handle)
--
1.9.1