On 2024/8/9 19:08, Muhammad Usama Anjum wrote:
> On 8/8/24 5:37 PM, Yunsheng Lin wrote:
>> The testing is done by ensuring that the fragment allocated
>> from a frag_frag_cache instance is pushed into a ptr_ring
>> instance in a kthread binded to a specified cpu, and a kthread
>> binded to a specified cpu will pop the fragment from the
>> ptr_ring and free the fragment.
>>
>> CC: Alexander Duyck <alexander.duyck@xxxxxxxxx>
>> Signed-off-by: Yunsheng Lin <linyunsheng@xxxxxxxxxx>
>> ---
>> tools/testing/selftests/mm/Makefile | 2 +
>> tools/testing/selftests/mm/page_frag/Makefile | 18 ++
>> .../selftests/mm/page_frag/page_frag_test.c | 170 ++++++++++++++++++
> Why are you adding a test module in kselftests? Have you considered
> adding Kunit instead? Kunit is more suited to test kernel's internal
> APIs which aren't exposed to userspace.
The main intent is to do performance impact of changing related to
page_frag, which is very much performance sensitive, so I am guessing
Kunit is not a right choice here if I am understanding it correctly.
>
>> tools/testing/selftests/mm/run_vmtests.sh | 9 +-
>> 4 files changed, 198 insertions(+), 1 deletion(-)
>> create mode 100644 tools/testing/selftests/mm/page_frag/Makefile
>> create mode 100644 tools/testing/selftests/mm/page_frag/page_frag_test.c
>>
>> diff --git a/tools/testing/selftests/mm/Makefile b/tools/testing/selftests/mm/Makefile
>> index 901e0d07765b..e91ed29378fc 100644
>> --- a/tools/testing/selftests/mm/Makefile
>> +++ b/tools/testing/selftests/mm/Makefile
>> @@ -36,6 +36,8 @@ MAKEFLAGS += --no-builtin-rules
>> CFLAGS = -Wall -I $(top_srcdir) $(EXTRA_CFLAGS) $(KHDR_INCLUDES) $(TOOLS_INCLUDES)
>> LDLIBS = -lrt -lpthread -lm
>>
>> +TEST_GEN_MODS_DIR := page_frag
>> +
>> TEST_GEN_FILES = cow
>> TEST_GEN_FILES += compaction_test
>> TEST_GEN_FILES += gup_longterm
>> diff --git a/tools/testing/selftests/mm/page_frag/Makefile b/tools/testing/selftests/mm/page_frag/Makefile
>> new file mode 100644
>> index 000000000000..58dda74d50a3
>> --- /dev/null
>> +++ b/tools/testing/selftests/mm/page_frag/Makefile
>> @@ -0,0 +1,18 @@
>> +PAGE_FRAG_TEST_DIR := $(realpath $(dir $(abspath $(lastword $(MAKEFILE_LIST)))))
>> +KDIR ?= $(abspath $(PAGE_FRAG_TEST_DIR)/../../../../..)
>> +
>> +ifeq ($(V),1)
>> +Q =
>> +else
>> +Q = @
>> +endif
>> +
>> +MODULES = page_frag_test.ko
>> +
>> +obj-m += page_frag_test.o
>> +
>> +all:
>> + +$(Q)make -C $(KDIR) M=$(PAGE_FRAG_TEST_DIR) modules
>> +
>> +clean:
>> + +$(Q)make -C $(KDIR) M=$(PAGE_FRAG_TEST_DIR) clean
>> diff --git a/tools/testing/selftests/mm/page_frag/page_frag_test.c b/tools/testing/selftests/mm/page_frag/page_frag_test.c
>> new file mode 100644
>> index 000000000000..0e803db1ad79
>> --- /dev/null
>> +++ b/tools/testing/selftests/mm/page_frag/page_frag_test.c
>> @@ -0,0 +1,170 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +
>> +/*
>> + * Test module for page_frag cache
>> + *
>> + * Copyright: linyunsheng@xxxxxxxxxx
>> + */
>> +
>> +#include <linux/mm.h>
>> +#include <linux/module.h>
>> +#include <linux/cpumask.h>
>> +#include <linux/completion.h>
>> +#include <linux/ptr_ring.h>
>> +#include <linux/kthread.h>
>> +
>> +static struct ptr_ring ptr_ring;
>> +static int nr_objs = 512;
>> +static atomic_t nthreads;
>> +static struct completion wait;
>> +static struct page_frag_cache test_frag;
>> +
>> +static int nr_test = 5120000;
>> +module_param(nr_test, int, 0);
>> +MODULE_PARM_DESC(nr_test, "number of iterations to test");
>> +
>> +static bool test_align;
>> +module_param(test_align, bool, 0);
>> +MODULE_PARM_DESC(test_align, "use align API for testing");
>> +
>> +static int test_alloc_len = 2048;
>> +module_param(test_alloc_len, int, 0);
>> +MODULE_PARM_DESC(test_alloc_len, "alloc len for testing");
>> +
>> +static int test_push_cpu;
>> +module_param(test_push_cpu, int, 0);
>> +MODULE_PARM_DESC(test_push_cpu, "test cpu for pushing fragment");
>> +
>> +static int test_pop_cpu;
>> +module_param(test_pop_cpu, int, 0);
>> +MODULE_PARM_DESC(test_pop_cpu, "test cpu for popping fragment");
>> +
>> +static int page_frag_pop_thread(void *arg)
>> +{
>> + struct ptr_ring *ring = arg;
>> + int nr = nr_test;
>> +
>> + pr_info("page_frag pop test thread begins on cpu %d\n",
>> + smp_processor_id());
>> +
>> + while (nr > 0) {
>> + void *obj = __ptr_ring_consume(ring);
>> +
>> + if (obj) {
>> + nr--;
>> + page_frag_free(obj);
>> + } else {
>> + cond_resched();
>> + }
>> + }
>> +
>> + if (atomic_dec_and_test(&nthreads))
>> + complete(&wait);
>> +
>> + pr_info("page_frag pop test thread exits on cpu %d\n",
>> + smp_processor_id());
>> +
>> + return 0;
>> +}
>> +
>> +static int page_frag_push_thread(void *arg)
>> +{
>> + struct ptr_ring *ring = arg;
>> + int nr = nr_test;
>> +
>> + pr_info("page_frag push test thread begins on cpu %d\n",
>> + smp_processor_id());
>> +
>> + while (nr > 0) {
>> + void *va;
>> + int ret;
>> +
>> + if (test_align) {
>> + va = page_frag_alloc_align(&test_frag, test_alloc_len,
>> + GFP_KERNEL, SMP_CACHE_BYTES);
>> +
>> + WARN_ONCE((unsigned long)va & (SMP_CACHE_BYTES - 1),
>> + "unaligned va returned\n");
>> + } else {
>> + va = page_frag_alloc(&test_frag, test_alloc_len, GFP_KERNEL);
>> + }
>> +
>> + if (!va)
>> + continue;
>> +
>> + ret = __ptr_ring_produce(ring, va);
>> + if (ret) {
>> + page_frag_free(va);
>> + cond_resched();
>> + } else {
>> + nr--;
>> + }
>> + }
>> +
>> + pr_info("page_frag push test thread exits on cpu %d\n",
>> + smp_processor_id());
>> +
>> + if (atomic_dec_and_test(&nthreads))
>> + complete(&wait);
>> +
>> + return 0;
>> +}
>> +
>> +static int __init page_frag_test_init(void)
>> +{
>> + struct task_struct *tsk_push, *tsk_pop;
>> + ktime_t start;
>> + u64 duration;
>> + int ret;
>> +
>> + test_frag.va = NULL;
>> + atomic_set(&nthreads, 2);
>> + init_completion(&wait);
>> +
>> + if (test_alloc_len > PAGE_SIZE || test_alloc_len <= 0 ||
>> + !cpu_active(test_push_cpu) || !cpu_active(test_pop_cpu))
>> + return -EINVAL;
>> +
>> + ret = ptr_ring_init(&ptr_ring, nr_objs, GFP_KERNEL);
>> + if (ret)
>> + return ret;
>> +
>> + tsk_push = kthread_create_on_cpu(page_frag_push_thread, &ptr_ring,
>> + test_push_cpu, "page_frag_push");
>> + if (IS_ERR(tsk_push))
>> + return PTR_ERR(tsk_push);
>> +
>> + tsk_pop = kthread_create_on_cpu(page_frag_pop_thread, &ptr_ring,
>> + test_pop_cpu, "page_frag_pop");
>> + if (IS_ERR(tsk_pop)) {
>> + kthread_stop(tsk_push);
>> + return PTR_ERR(tsk_pop);
>> + }
>> +
>> + start = ktime_get();
>> + wake_up_process(tsk_push);
>> + wake_up_process(tsk_pop);
>> +
>> + pr_info("waiting for test to complete\n");
>> + wait_for_completion(&wait);
>> +
>> + duration = (u64)ktime_us_delta(ktime_get(), start);
>> + pr_info("%d of iterations for %s testing took: %lluus\n", nr_test,
>> + test_align ? "aligned" : "non-aligned", duration);
>> +
>> + ptr_ring_cleanup(&ptr_ring, NULL);
>> + page_frag_cache_drain(&test_frag);
>> +
>> + return -EAGAIN;
>> +}
>> +
>> +static void __exit page_frag_test_exit(void)
>> +{
>> +}
>> +
>> +module_init(page_frag_test_init);
>> +module_exit(page_frag_test_exit);
>> +
>> +MODULE_LICENSE("GPL");
>> +MODULE_AUTHOR("Yunsheng Lin <linyunsheng@xxxxxxxxxx>");
>> +MODULE_DESCRIPTION("Test module for page_frag");
>> diff --git a/tools/testing/selftests/mm/run_vmtests.sh b/tools/testing/selftests/mm/run_vmtests.sh
>> index 03ac4f2e1cce..3636d984b786 100755
>> --- a/tools/testing/selftests/mm/run_vmtests.sh
>> +++ b/tools/testing/selftests/mm/run_vmtests.sh
>> @@ -75,6 +75,8 @@ separated by spaces:
>> read-only VMAs
>> - mdwe
>> test prctl(PR_SET_MDWE, ...)
>> +- page_frag
>> + test handling of page fragment allocation and freeing
>>
>> example: ./run_vmtests.sh -t "hmm mmap ksm"
>> EOF
>> @@ -231,7 +233,8 @@ run_test() {
>> ("$@" 2>&1) | tap_prefix
>> local ret=${PIPESTATUS[0]}
>> count_total=$(( count_total + 1 ))
>> - if [ $ret -eq 0 ]; then
>> + # page_frag_test.ko returns 11(EAGAIN) when insmod'ing to avoid rmmod
>> + if [ $ret -eq 0 ] | [ $ret -eq 11 -a ${CATEGORY} == "page_frag" ]; then
>> count_pass=$(( count_pass + 1 ))
>> echo "[PASS]" | tap_prefix
>> echo "ok ${count_total} ${test}" | tap_output
>> @@ -453,6 +456,10 @@ CATEGORY="mkdirty" run_test ./mkdirty
>>
>> CATEGORY="mdwe" run_test ./mdwe_test
>>
>> +CATEGORY="page_frag" run_test insmod ./page_frag/page_frag_test.ko
>> +
>> +CATEGORY="page_frag" run_test insmod ./page_frag/page_frag_test.ko test_alloc_len=12 test_align=1
>> +
> You are loading the test module. How will we verify if the test passed
> or failed? There must be a way to mark the test passed or failed after
I am not sure that matter that much for page_frag_test module as it
already return -EAGAIN for normal case as mentioned in:
https://patchwork.kernel.org/project/netdevbpf/patch/20240731124505.2903877-2-linyunsheng@xxxxxxxxxx/#25960885
> running it. You can definitely parse the dmesg to get results. But it
> would be complex to do it. KUnit is way to go as all such tools are
> already present there.
