Re: [PATCH V2 2/2] zswap: Add module parameter malloc_movable_if_support

From: Shakeel Butt
Date: Tue Jun 04 2019 - 13:16:08 EST

On Sun, Jun 2, 2019 at 2:47 AM Hui Zhu <teawaterz@xxxxxxxxxxxxxxxxx> wrote:
>
> This is the second version that was updated according to the comments
> from Sergey Senozhatsky in https://lkml.org/lkml/2019/5/29/73
>
> 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);
>
> And commit "zpool: Add malloc_support_movable to zpool_driver" add
> zpool_malloc_support_movable check malloc_support_movable to make
> sure if a zpool support allocate movable memory.
>
> This commit adds module parameter malloc_movable_if_support to enable
> or disable zpool allocate block with gfp __GFP_HIGHMEM | __GFP_MOVABLE
> if it support allocate movable memory (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 / 3977932 usecs = 667233 KB/s
> 2717908992 bytes / 4160702 usecs = 637923 KB/s
> 2717908992 bytes / 4354611 usecs = 609516 KB/s
> 293359 usecs to free memory
> 340304 usecs to free memory
> 205781 usecs to free memory
> 2717908992 bytes / 5588016 usecs = 474982 KB/s
> 166124 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 5 10 9 8 8 5 1 2 3 0 0
> Node 0, zone DMA32, type Movable 15 16 14 12 14 10 9 6 6 5 776
> 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 7097 6914 6473 5642 4373 2664 1220 319 78 4 0
> Node 0, zone Normal, type Movable 2092 3216 2820 2266 1585 946 559 359 237 258 378
> Node 0, zone Normal, type Reclaimable 47 88 122 80 34 9 5 4 2 1 2
> 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 834 1572 25 0 0 0
>
> When it enabled:
> echo lz4 > /sys/module/zswap/parameters/compressor
> echo zsmalloc > /sys/module/zswap/parameters/zpool
> echo 1 > /sys/module/zswap/parameters/enabled
> echo 1 > /sys/module/zswap/parameters/malloc_movable_if_support
> 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 / 4721401 usecs = 562165 KB/s
> 2717908992 bytes / 4783167 usecs = 554905 KB/s
> 2717908992 bytes / 4802125 usecs = 552715 KB/s
> 2717908992 bytes / 4866579 usecs = 545395 KB/s
> 323605 usecs to free memory
> 414817 usecs to free memory
> 458576 usecs to free memory
> 355827 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 8 10 8 7 7 6 5 3 2 0 0
> Node 0, zone DMA32, type Movable 23 21 18 15 13 14 14 10 11 6 766
> 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 2660 1295 460 102 11 5 3 11 2 4 0
> Node 0, zone Normal, type Movable 4178 5760 5045 4137 3324 2306 1482 930 497 254 460
> Node 0, zone Normal, type Reclaimable 50 83 114 93 28 12 10 6 3 3 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 81 2325 25 0 0 0
>
> You can see that the number of unmovable page blocks is decreased
> when malloc_movable_if_support is enabled.
>
> Signed-off-by: Hui Zhu <teawaterz@xxxxxxxxxxxxxxxxx>
> ---
> mm/zswap.c | 16 +++++++++++++---
> 1 file changed, 13 insertions(+), 3 deletions(-)
>
> diff --git a/mm/zswap.c b/mm/zswap.c
> index a4e4d36ec085..2fc45de92383 100644
> --- a/mm/zswap.c
> +++ b/mm/zswap.c
> @@ -123,6 +123,13 @@ static bool zswap_same_filled_pages_enabled = true;
> module_param_named(same_filled_pages_enabled, zswap_same_filled_pages_enabled,
> bool, 0644);
>
> +/* Enable/disable zpool allocate block with gfp __GFP_HIGHMEM | __GFP_MOVABLE
> + * if it support allocate movable memory (disabled by default).
> + */
> +static bool __read_mostly zswap_malloc_movable_if_support;
> +module_param_cb(malloc_movable_if_support, &param_ops_bool,
> + &zswap_malloc_movable_if_support, 0644);
> +

Any reason for the above tunable? Do we ever want to disable movable
for zswap+zsmalloc?

> /*********************************
> * data structures
> **********************************/
> @@ -1006,6 +1013,7 @@ static int zswap_frontswap_store(unsigned type, pgoff_t offset,
> char *buf;
> u8 *src, *dst;
> struct zswap_header zhdr = { .swpentry = swp_entry(type, offset) };
> + gfp_t gfp = __GFP_NORETRY | __GFP_NOWARN | __GFP_KSWAPD_RECLAIM;
>
> /* THP isn't supported */
> if (PageTransHuge(page)) {
> @@ -1079,9 +1087,11 @@ static int zswap_frontswap_store(unsigned type, pgoff_t offset,
>
> /* store */
> hlen = zpool_evictable(entry->pool->zpool) ? sizeof(zhdr) : 0;
> - ret = zpool_malloc(entry->pool->zpool, hlen + dlen,
> - __GFP_NORETRY | __GFP_NOWARN | __GFP_KSWAPD_RECLAIM,
> - &handle);
> + if (zswap_malloc_movable_if_support &&
> + zpool_malloc_support_movable(entry->pool->zpool)) {
> + gfp |= __GFP_HIGHMEM | __GFP_MOVABLE;
> + }
> + ret = zpool_malloc(entry->pool->zpool, hlen + dlen, gfp, &handle);
> if (ret == -ENOSPC) {
> zswap_reject_compress_poor++;
> goto put_dstmem;
> --
> 2.20.1 (Apple Git-117)
>