[UPSTREAM KERNEL] mm/zsmalloc.c: Add module parameter malloc_force_movable

From: Hui Zhu
Date: Tue May 28 2019 - 21:26:20 EST

zswap compresses swap pages into a dynamically allocated RAM-based
memory pool. The memory pool should be zbud, z3fold or zsmalloc.
All of them will allocate unmovable pages. It will increase the
number of unmovable page blocks that will bad for anti-fragment.

zsmalloc support page migration if request movable page:
handle = zs_malloc(zram->mem_pool, comp_len,
GFP_NOIO | __GFP_HIGHMEM |
__GFP_MOVABLE);

This commit adds module parameter malloc_force_movable to enable
or disable zs_malloc force allocate block with gfp
__GFP_HIGHMEM | __GFP_MOVABLE (disabled by default).

Following part is test log in a pc that has 8G memory and 2G swap.

When it disabled:
~# echo lz4 > /sys/module/zswap/parameters/compressor
~# echo zsmalloc > /sys/module/zswap/parameters/zpool
~# echo 1 > /sys/module/zswap/parameters/enabled
~# swapon /swapfile
~# cd /home/teawater/kernel/vm-scalability/
/home/teawater/kernel/vm-scalability# export unit_size=$((9 * 1024 * 1024 * 1024))
/home/teawater/kernel/vm-scalability# ./case-anon-w-seq
2717908992 bytes / 4410183 usecs = 601836 KB/s
2717908992 bytes / 4524375 usecs = 586646 KB/s
2717908992 bytes / 4558583 usecs = 582244 KB/s
2717908992 bytes / 4824261 usecs = 550179 KB/s
348046 usecs to free memory
401680 usecs to free memory
369660 usecs to free memory
180867 usecs to free memory
/home/teawater/kernel/vm-scalability# cat /proc/pagetypeinfo
Page block order: 9
Pages per block: 512

Free pages count per migrate type at order 0 1 2 3 4 5 6 7 8 9 10
Node 0, zone DMA, type Unmovable 1 1 1 0 2 1 1 0 1 0 0
Node 0, zone DMA, type Movable 0 0 0 0 0 0 0 0 0 1 3
Node 0, zone DMA, type Reclaimable 0 0 0 0 0 0 0 0 0 0 0
Node 0, zone DMA, type HighAtomic 0 0 0 0 0 0 0 0 0 0 0
Node 0, zone DMA, type CMA 0 0 0 0 0 0 0 0 0 0 0
Node 0, zone DMA, type Isolate 0 0 0 0 0 0 0 0 0 0 0
Node 0, zone DMA32, type Unmovable 13 11 10 11 10 6 7 3 1 0 0
Node 0, zone DMA32, type Movable 36 26 39 40 37 36 24 29 14 6 767
Node 0, zone DMA32, type Reclaimable 0 0 0 0 0 0 0 0 0 0 1
Node 0, zone DMA32, type HighAtomic 0 0 0 0 0 0 0 0 0 0 0
Node 0, zone DMA32, type CMA 0 0 0 0 0 0 0 0 0 0 0
Node 0, zone DMA32, type Isolate 0 0 0 0 0 0 0 0 0 0 0
Node 0, zone Normal, type Unmovable 7744 7519 6900 5964 4583 2878 1346 448 146 1 0
Node 0, zone Normal, type Movable 645 1930 1685 1339 1020 670 363 210 106 310 399
Node 0, zone Normal, type Reclaimable 53 70 116 48 13 0 0 0 0 0 0
Node 0, zone Normal, type HighAtomic 0 0 0 0 0 0 0 0 0 0 0
Node 0, zone Normal, type CMA 0 0 0 0 0 0 0 0 0 0 0
Node 0, zone Normal, type Isolate 0 0 0 0 0 0 0 0 0 0 0

Number of blocks type Unmovable Movable Reclaimable HighAtomic CMA Isolate
Node 0, zone DMA 1 7 0 0 0 0
Node 0, zone DMA32 4 1650 2 0 0 0
Node 0, zone Normal 947 1469 15 0 0 0

When it enabled:
~# echo 1 > /sys/module/zsmalloc/parameters/malloc_force_movable
~# echo lz4 > /sys/module/zswap/parameters/compressor
~# echo zsmalloc > /sys/module/zswap/parameters/zpool
~# echo 1 > /sys/module/zswap/parameters/enabled
~# swapon /swapfile
~# cd /home/teawater/kernel/vm-scalability/
/home/teawater/kernel/vm-scalability# export unit_size=$((9 * 1024 * 1024 * 1024))
/home/teawater/kernel/vm-scalability# ./case-anon-w-seq
2717908992 bytes / 4779235 usecs = 555362 KB/s
2717908992 bytes / 4856673 usecs = 546507 KB/s
2717908992 bytes / 4920079 usecs = 539464 KB/s
2717908992 bytes / 4935505 usecs = 537778 KB/s
354839 usecs to free memory
368167 usecs to free memory
355460 usecs to free memory
385452 usecs to free memory
/home/teawater/kernel/vm-scalability# cat /proc/pagetypeinfo
Page block order: 9
Pages per block: 512

Free pages count per migrate type at order 0 1 2 3 4 5 6 7 8 9 10
Node 0, zone DMA, type Unmovable 1 1 1 0 2 1 1 0 1 0 0
Node 0, zone DMA, type Movable 0 0 0 0 0 0 0 0 0 1 3
Node 0, zone DMA, type Reclaimable 0 0 0 0 0 0 0 0 0 0 0
Node 0, zone DMA, type HighAtomic 0 0 0 0 0 0 0 0 0 0 0
Node 0, zone DMA, type CMA 0 0 0 0 0 0 0 0 0 0 0
Node 0, zone DMA, type Isolate 0 0 0 0 0 0 0 0 0 0 0
Node 0, zone DMA32, type Unmovable 9 15 13 10 13 9 3 2 2 0 0
Node 0, zone DMA32, type Movable 16 19 10 14 17 17 16 8 5 6 775
Node 0, zone DMA32, type Reclaimable 0 0 0 0 0 0 0 0 0 0 0
Node 0, zone DMA32, type HighAtomic 0 0 0 0 0 0 0 0 0 0 0
Node 0, zone DMA32, type CMA 0 0 0 0 0 0 0 0 0 0 0
Node 0, zone DMA32, type Isolate 0 0 0 0 0 0 0 0 0 0 0
Node 0, zone Normal, type Unmovable 2525 1347 603 181 55 14 4 1 6 0 0
Node 0, zone Normal, type Movable 5255 6069 5007 3978 2885 1940 1164 732 485 276 511
Node 0, zone Normal, type Reclaimable 103 104 140 87 31 21 7 3 2 1 1
Node 0, zone Normal, type HighAtomic 0 0 0 0 0 0 0 0 0 0 0
Node 0, zone Normal, type CMA 0 0 0 0 0 0 0 0 0 0 0
Node 0, zone Normal, type Isolate 0 0 0 0 0 0 0 0 0 0 0

Number of blocks type Unmovable Movable Reclaimable HighAtomic CMA Isolate
Node 0, zone DMA 1 7 0 0 0 0
Node 0, zone DMA32 4 1652 0 0 0 0
Node 0, zone Normal 78 2330 23 0 0 0

You can see that the number of unmovable page blocks is decreased
when malloc_force_movable is enabled.

Signed-off-by: Hui Zhu <teawaterz@xxxxxxxxxxxxxxxxx>
---
mm/zsmalloc.c | 10 ++++++++++
1 file changed, 10 insertions(+)

diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index 0787d33b80d8..7d44c7ccd882 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -178,6 +178,13 @@ static struct dentry *zs_stat_root;
static struct vfsmount *zsmalloc_mnt;
#endif

+/* Enable/disable zs_malloc force allocate block with
+ * gfp __GFP_HIGHMEM | __GFP_MOVABLE (disabled by default).
+ */
+static bool __read_mostly zs_malloc_force_movable;
+module_param_cb(malloc_force_movable, &param_ops_bool,
+ &zs_malloc_force_movable, 0644);
+
/*
* We assign a page to ZS_ALMOST_EMPTY fullness group when:
* n <= N / f, where
@@ -1479,6 +1486,9 @@ unsigned long zs_malloc(struct zs_pool *pool, size_t size, gfp_t gfp)
if (unlikely(!size || size > ZS_MAX_ALLOC_SIZE))
return 0;

+ if (zs_malloc_force_movable)
+ gfp |= __GFP_HIGHMEM | __GFP_MOVABLE;
+
handle = cache_alloc_handle(pool, gfp);
if (!handle)
return 0;
--
2.20.1 (Apple Git-117)