Barry Song 21cnbao@gmail.com writes:
On Thu, Jun 20, 2024 at 1:55 PM Huang, Ying ying.huang@intel.com wrote:
Barry Song 21cnbao@gmail.com writes:
From: Barry Song v-songbaohua@oppo.com
Both Ryan and Chris have been utilizing the small test program to aid in debugging and identifying issues with swap entry allocation. While a real or intricate workload might be more suitable for assessing the correctness and effectiveness of the swap allocation policy, a small test program presents a simpler means of understanding the problem and initially verifying the improvements being made.
Let's endeavor to integrate it into the self-test suite. Although it presently only accommodates 64KB and 4KB, I'm optimistic that we can expand its capabilities to support multiple sizes and simulate more complex systems in the future as required.
IIUC, this is a performance test program instead of functionality test program. Does it match the purpose of the kernel selftest?
I have a differing perspective. I maintain that the functionality is not functioning as expected. Despite having all the necessary resources for allocation, failure persists, indicating a lack of functionality.
Is there any user visual functionality issue?
Signed-off-by: Barry Song v-songbaohua@oppo.com
tools/testing/selftests/mm/Makefile | 1 + .../selftests/mm/thp_swap_allocator_test.c | 192 ++++++++++++++++++ 2 files changed, 193 insertions(+) create mode 100644 tools/testing/selftests/mm/thp_swap_allocator_test.c
diff --git a/tools/testing/selftests/mm/Makefile b/tools/testing/selftests/mm/Makefile index e1aa09ddaa3d..64164ad66835 100644 --- a/tools/testing/selftests/mm/Makefile +++ b/tools/testing/selftests/mm/Makefile @@ -65,6 +65,7 @@ TEST_GEN_FILES += mseal_test TEST_GEN_FILES += seal_elf TEST_GEN_FILES += on-fault-limit TEST_GEN_FILES += pagemap_ioctl +TEST_GEN_FILES += thp_swap_allocator_test TEST_GEN_FILES += thuge-gen TEST_GEN_FILES += transhuge-stress TEST_GEN_FILES += uffd-stress diff --git a/tools/testing/selftests/mm/thp_swap_allocator_test.c b/tools/testing/selftests/mm/thp_swap_allocator_test.c new file mode 100644 index 000000000000..4443a906d0f8 --- /dev/null +++ b/tools/testing/selftests/mm/thp_swap_allocator_test.c @@ -0,0 +1,192 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/*
- thp_swap_allocator_test
- The purpose of this test program is helping check if THP swpout
- can correctly get swap slots to swap out as a whole instead of
- being split. It randomly releases swap entries through madvise
- DONTNEED and do swapout on two memory areas: a memory area for
- 64KB THP and the other area for small folios. The second memory
- can be enabled by "-s".
- Before running the program, we need to setup a zRAM or similar
- swap device by:
- echo lzo > /sys/block/zram0/comp_algorithm
- echo 64M > /sys/block/zram0/disksize
- echo never > /sys/kernel/mm/transparent_hugepage/hugepages-2048kB/enabled
- echo always > /sys/kernel/mm/transparent_hugepage/hugepages-64kB/enabled
- mkswap /dev/zram0
- swapon /dev/zram0
- The expected result should be 0% anon swpout fallback ratio w/ or
- w/o "-s".
- Author(s): Barry Song v-songbaohua@oppo.com
- */
+#define _GNU_SOURCE +#include <stdio.h> +#include <stdlib.h> +#include <unistd.h> +#include <string.h> +#include <sys/mman.h> +#include <errno.h> +#include <time.h>
+#define MEMSIZE_MTHP (60 * 1024 * 1024) +#define MEMSIZE_SMALLFOLIO (1 * 1024 * 1024) +#define ALIGNMENT_MTHP (64 * 1024) +#define ALIGNMENT_SMALLFOLIO (4 * 1024) +#define TOTAL_DONTNEED_MTHP (16 * 1024 * 1024) +#define TOTAL_DONTNEED_SMALLFOLIO (768 * 1024) +#define MTHP_FOLIO_SIZE (64 * 1024)
+#define SWPOUT_PATH \
"/sys/kernel/mm/transparent_hugepage/hugepages-64kB/stats/swpout"+#define SWPOUT_FALLBACK_PATH \
"/sys/kernel/mm/transparent_hugepage/hugepages-64kB/stats/swpout_fallback"+static void *aligned_alloc_mem(size_t size, size_t alignment) +{
void *mem = NULL;if (posix_memalign(&mem, alignment, size) != 0) {perror("posix_memalign");return NULL;}return mem;+}
+static void random_madvise_dontneed(void *mem, size_t mem_size,
size_t align_size, size_t total_dontneed_size)+{
size_t num_pages = total_dontneed_size / align_size;size_t i;size_t offset;void *addr;for (i = 0; i < num_pages; ++i) {offset = (rand() % (mem_size / align_size)) * align_size;addr = (char *)mem + offset;if (madvise(addr, align_size, MADV_DONTNEED) != 0)perror("madvise dontneed");IIUC, this simulates align_size (generally 64KB) swap-in. That is, it simulate the effect of large size swap-in when it's not available in kernel. If we have large size swap-in in kernel in the future, this becomes unnecessary.
Additionally, we have not reached the consensus that we should always swap-in with swapped-out size. So, I suspect that this test may not reflect real situation in the future. Although it doesn't reflect current situation too.
Disagree again. releasing the whole mTHP swaps is the best case. Even in the best-case scenario, if we fail, it raises concerns for handling potentially more challenging situations.
Repeating sequential anonymous pages writing is the best case.
I don't find it hard to incorporate additional features into this test program to simulate more intricate scenarios.
IMHO, we don't really need this special purpose test. We can have some more general basic tests, for example, sequential anonymous pages writing/reading, random anonymous pages writing/reading, and combination of them.
-- Best Regards, Huang, Ying
memset(addr, 0x11, align_size);}+}
[snip]
-- Best Regards, Huang, Ying
Thanks Barry