Re: [PATCH v9 09/10] selftests/mm/cow: Generalize do_run_with_thp() helper

From: Ryan Roberts
Date: Wed Jan 03 2024 - 03:34:14 EST

On 03/01/2024 06:21, Itaru Kitayama wrote:
> On Thu, Dec 07, 2023 at 04:12:10PM +0000, Ryan Roberts wrote:
>> do_run_with_thp() prepares (PMD-sized) THP memory into different states
>> before running tests. With the introduction of multi-size THP, we would
>> like to reuse this logic to also test those smaller THP sizes. So let's
>> add a thpsize parameter which tells the function what size THP it should
>> operate on.
>>
>> A separate commit will utilize this change to add new tests for
>> multi-size THP, where available.
>>
>> Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
>> Tested-by: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
>> Tested-by: John Hubbard <jhubbard@xxxxxxxxxx>
>> Signed-off-by: Ryan Roberts <ryan.roberts@xxxxxxx>
>
> Tested-by: Itaru Kitayama <itaru.kitayama@xxxxxxxxx>

Thanks for testing!

>
> I am replying to all this time; Ryan, do you think it's okay to run
> 700 of selftests/mm/cow tests? Even on FVP, they did not take longer
> though.

What exactly is your concern, the amount of time it takes to run the tests? I've
found (at least on real HW) that the time it takes to run a test is dominated by
accessing the folio's memory. So adding all of the new tests that test sizes
between order-2 and PMD_ORDER-1 is ~equivalent to running the existing PMD_ORDER
tests twice. And the runtime of those is barely noticable compared to the
PUD_ORDER HugeTLB tests. So I don't think we are impacting runtime by much.
Sounds like your experience says that's also true for FVP?

>
>> ---
>> tools/testing/selftests/mm/cow.c | 121 +++++++++++++++++--------------
>> 1 file changed, 67 insertions(+), 54 deletions(-)
>>
>> diff --git a/tools/testing/selftests/mm/cow.c b/tools/testing/selftests/mm/cow.c
>> index 7324ce5363c0..4d0b5a125d3c 100644
>> --- a/tools/testing/selftests/mm/cow.c
>> +++ b/tools/testing/selftests/mm/cow.c
>> @@ -32,7 +32,7 @@
>>
>> static size_t pagesize;
>> static int pagemap_fd;
>> -static size_t thpsize;
>> +static size_t pmdsize;
>> static int nr_hugetlbsizes;
>> static size_t hugetlbsizes[10];
>> static int gup_fd;
>> @@ -734,7 +734,7 @@ enum thp_run {
>> THP_RUN_PARTIAL_SHARED,
>> };
>>
>> -static void do_run_with_thp(test_fn fn, enum thp_run thp_run)
>> +static void do_run_with_thp(test_fn fn, enum thp_run thp_run, size_t thpsize)
>> {
>> char *mem, *mmap_mem, *tmp, *mremap_mem = MAP_FAILED;
>> size_t size, mmap_size, mremap_size;
>> @@ -759,11 +759,11 @@ static void do_run_with_thp(test_fn fn, enum thp_run thp_run)
>> }
>>
>> /*
>> - * Try to populate a THP. Touch the first sub-page and test if we get
>> - * another sub-page populated automatically.
>> + * Try to populate a THP. Touch the first sub-page and test if
>> + * we get the last sub-page populated automatically.
>> */
>> mem[0] = 0;
>> - if (!pagemap_is_populated(pagemap_fd, mem + pagesize)) {
>> + if (!pagemap_is_populated(pagemap_fd, mem + thpsize - pagesize)) {
>> ksft_test_result_skip("Did not get a THP populated\n");
>> goto munmap;
>> }
>> @@ -773,12 +773,14 @@ static void do_run_with_thp(test_fn fn, enum thp_run thp_run)
>> switch (thp_run) {
>> case THP_RUN_PMD:
>> case THP_RUN_PMD_SWAPOUT:
>> + assert(thpsize == pmdsize);
>> break;
>> case THP_RUN_PTE:
>> case THP_RUN_PTE_SWAPOUT:
>> /*
>> * Trigger PTE-mapping the THP by temporarily mapping a single
>> - * subpage R/O.
>> + * subpage R/O. This is a noop if the THP is not pmdsize (and
>> + * therefore already PTE-mapped).
>> */
>> ret = mprotect(mem + pagesize, pagesize, PROT_READ);
>> if (ret) {
>> @@ -875,52 +877,60 @@ static void do_run_with_thp(test_fn fn, enum thp_run thp_run)
>> munmap(mremap_mem, mremap_size);
>> }
>>
>> -static void run_with_thp(test_fn fn, const char *desc)
>> +static void run_with_thp(test_fn fn, const char *desc, size_t size)
>> {
>> - ksft_print_msg("[RUN] %s ... with THP\n", desc);
>> - do_run_with_thp(fn, THP_RUN_PMD);
>> + ksft_print_msg("[RUN] %s ... with THP (%zu kB)\n",
>> + desc, size / 1024);
>> + do_run_with_thp(fn, THP_RUN_PMD, size);
>> }
>>
>> -static void run_with_thp_swap(test_fn fn, const char *desc)
>> +static void run_with_thp_swap(test_fn fn, const char *desc, size_t size)
>> {
>> - ksft_print_msg("[RUN] %s ... with swapped-out THP\n", desc);
>> - do_run_with_thp(fn, THP_RUN_PMD_SWAPOUT);
>> + ksft_print_msg("[RUN] %s ... with swapped-out THP (%zu kB)\n",
>> + desc, size / 1024);
>> + do_run_with_thp(fn, THP_RUN_PMD_SWAPOUT, size);
>> }
>>
>> -static void run_with_pte_mapped_thp(test_fn fn, const char *desc)
>> +static void run_with_pte_mapped_thp(test_fn fn, const char *desc, size_t size)
>> {
>> - ksft_print_msg("[RUN] %s ... with PTE-mapped THP\n", desc);
>> - do_run_with_thp(fn, THP_RUN_PTE);
>> + ksft_print_msg("[RUN] %s ... with PTE-mapped THP (%zu kB)\n",
>> + desc, size / 1024);
>> + do_run_with_thp(fn, THP_RUN_PTE, size);
>> }
>>
>> -static void run_with_pte_mapped_thp_swap(test_fn fn, const char *desc)
>> +static void run_with_pte_mapped_thp_swap(test_fn fn, const char *desc, size_t size)
>> {
>> - ksft_print_msg("[RUN] %s ... with swapped-out, PTE-mapped THP\n", desc);
>> - do_run_with_thp(fn, THP_RUN_PTE_SWAPOUT);
>> + ksft_print_msg("[RUN] %s ... with swapped-out, PTE-mapped THP (%zu kB)\n",
>> + desc, size / 1024);
>> + do_run_with_thp(fn, THP_RUN_PTE_SWAPOUT, size);
>> }
>>
>> -static void run_with_single_pte_of_thp(test_fn fn, const char *desc)
>> +static void run_with_single_pte_of_thp(test_fn fn, const char *desc, size_t size)
>> {
>> - ksft_print_msg("[RUN] %s ... with single PTE of THP\n", desc);
>> - do_run_with_thp(fn, THP_RUN_SINGLE_PTE);
>> + ksft_print_msg("[RUN] %s ... with single PTE of THP (%zu kB)\n",
>> + desc, size / 1024);
>> + do_run_with_thp(fn, THP_RUN_SINGLE_PTE, size);
>> }
>>
>> -static void run_with_single_pte_of_thp_swap(test_fn fn, const char *desc)
>> +static void run_with_single_pte_of_thp_swap(test_fn fn, const char *desc, size_t size)
>> {
>> - ksft_print_msg("[RUN] %s ... with single PTE of swapped-out THP\n", desc);
>> - do_run_with_thp(fn, THP_RUN_SINGLE_PTE_SWAPOUT);
>> + ksft_print_msg("[RUN] %s ... with single PTE of swapped-out THP (%zu kB)\n",
>> + desc, size / 1024);
>> + do_run_with_thp(fn, THP_RUN_SINGLE_PTE_SWAPOUT, size);
>> }
>>
>> -static void run_with_partial_mremap_thp(test_fn fn, const char *desc)
>> +static void run_with_partial_mremap_thp(test_fn fn, const char *desc, size_t size)
>> {
>> - ksft_print_msg("[RUN] %s ... with partially mremap()'ed THP\n", desc);
>> - do_run_with_thp(fn, THP_RUN_PARTIAL_MREMAP);
>> + ksft_print_msg("[RUN] %s ... with partially mremap()'ed THP (%zu kB)\n",
>> + desc, size / 1024);
>> + do_run_with_thp(fn, THP_RUN_PARTIAL_MREMAP, size);
>> }
>>
>> -static void run_with_partial_shared_thp(test_fn fn, const char *desc)
>> +static void run_with_partial_shared_thp(test_fn fn, const char *desc, size_t size)
>> {
>> - ksft_print_msg("[RUN] %s ... with partially shared THP\n", desc);
>> - do_run_with_thp(fn, THP_RUN_PARTIAL_SHARED);
>> + ksft_print_msg("[RUN] %s ... with partially shared THP (%zu kB)\n",
>> + desc, size / 1024);
>> + do_run_with_thp(fn, THP_RUN_PARTIAL_SHARED, size);
>> }
>>
>> static void run_with_hugetlb(test_fn fn, const char *desc, size_t hugetlbsize)
>> @@ -1091,15 +1101,15 @@ static void run_anon_test_case(struct test_case const *test_case)
>>
>> run_with_base_page(test_case->fn, test_case->desc);
>> run_with_base_page_swap(test_case->fn, test_case->desc);
>> - if (thpsize) {
>> - run_with_thp(test_case->fn, test_case->desc);
>> - run_with_thp_swap(test_case->fn, test_case->desc);
>> - run_with_pte_mapped_thp(test_case->fn, test_case->desc);
>> - run_with_pte_mapped_thp_swap(test_case->fn, test_case->desc);
>> - run_with_single_pte_of_thp(test_case->fn, test_case->desc);
>> - run_with_single_pte_of_thp_swap(test_case->fn, test_case->desc);
>> - run_with_partial_mremap_thp(test_case->fn, test_case->desc);
>> - run_with_partial_shared_thp(test_case->fn, test_case->desc);
>> + if (pmdsize) {
>> + run_with_thp(test_case->fn, test_case->desc, pmdsize);
>> + run_with_thp_swap(test_case->fn, test_case->desc, pmdsize);
>> + run_with_pte_mapped_thp(test_case->fn, test_case->desc, pmdsize);
>> + run_with_pte_mapped_thp_swap(test_case->fn, test_case->desc, pmdsize);
>> + run_with_single_pte_of_thp(test_case->fn, test_case->desc, pmdsize);
>> + run_with_single_pte_of_thp_swap(test_case->fn, test_case->desc, pmdsize);
>> + run_with_partial_mremap_thp(test_case->fn, test_case->desc, pmdsize);
>> + run_with_partial_shared_thp(test_case->fn, test_case->desc, pmdsize);
>> }
>> for (i = 0; i < nr_hugetlbsizes; i++)
>> run_with_hugetlb(test_case->fn, test_case->desc,
>> @@ -1120,7 +1130,7 @@ static int tests_per_anon_test_case(void)
>> {
>> int tests = 2 + nr_hugetlbsizes;
>>
>> - if (thpsize)
>> + if (pmdsize)
>> tests += 8;
>> return tests;
>> }
>> @@ -1329,7 +1339,7 @@ static void run_anon_thp_test_cases(void)
>> {
>> int i;
>>
>> - if (!thpsize)
>> + if (!pmdsize)
>> return;
>>
>> ksft_print_msg("[INFO] Anonymous THP tests\n");
>> @@ -1338,13 +1348,13 @@ static void run_anon_thp_test_cases(void)
>> struct test_case const *test_case = &anon_thp_test_cases[i];
>>
>> ksft_print_msg("[RUN] %s\n", test_case->desc);
>> - do_run_with_thp(test_case->fn, THP_RUN_PMD);
>> + do_run_with_thp(test_case->fn, THP_RUN_PMD, pmdsize);
>> }
>> }
>>
>> static int tests_per_anon_thp_test_case(void)
>> {
>> - return thpsize ? 1 : 0;
>> + return pmdsize ? 1 : 0;
>> }
>>
>> typedef void (*non_anon_test_fn)(char *mem, const char *smem, size_t size);
>> @@ -1419,7 +1429,7 @@ static void run_with_huge_zeropage(non_anon_test_fn fn, const char *desc)
>> }
>>
>> /* For alignment purposes, we need twice the thp size. */
>> - mmap_size = 2 * thpsize;
>> + mmap_size = 2 * pmdsize;
>> mmap_mem = mmap(NULL, mmap_size, PROT_READ | PROT_WRITE,
>> MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
>> if (mmap_mem == MAP_FAILED) {
>> @@ -1434,11 +1444,11 @@ static void run_with_huge_zeropage(non_anon_test_fn fn, const char *desc)
>> }
>>
>> /* We need a THP-aligned memory area. */
>> - mem = (char *)(((uintptr_t)mmap_mem + thpsize) & ~(thpsize - 1));
>> - smem = (char *)(((uintptr_t)mmap_smem + thpsize) & ~(thpsize - 1));
>> + mem = (char *)(((uintptr_t)mmap_mem + pmdsize) & ~(pmdsize - 1));
>> + smem = (char *)(((uintptr_t)mmap_smem + pmdsize) & ~(pmdsize - 1));
>>
>> - ret = madvise(mem, thpsize, MADV_HUGEPAGE);
>> - ret |= madvise(smem, thpsize, MADV_HUGEPAGE);
>> + ret = madvise(mem, pmdsize, MADV_HUGEPAGE);
>> + ret |= madvise(smem, pmdsize, MADV_HUGEPAGE);
>> if (ret) {
>> ksft_test_result_fail("MADV_HUGEPAGE failed\n");
>> goto munmap;
>> @@ -1457,7 +1467,7 @@ static void run_with_huge_zeropage(non_anon_test_fn fn, const char *desc)
>> goto munmap;
>> }
>>
>> - fn(mem, smem, thpsize);
>> + fn(mem, smem, pmdsize);
>> munmap:
>> munmap(mmap_mem, mmap_size);
>> if (mmap_smem != MAP_FAILED)
>> @@ -1650,7 +1660,7 @@ static void run_non_anon_test_case(struct non_anon_test_case const *test_case)
>> run_with_zeropage(test_case->fn, test_case->desc);
>> run_with_memfd(test_case->fn, test_case->desc);
>> run_with_tmpfile(test_case->fn, test_case->desc);
>> - if (thpsize)
>> + if (pmdsize)
>> run_with_huge_zeropage(test_case->fn, test_case->desc);
>> for (i = 0; i < nr_hugetlbsizes; i++)
>> run_with_memfd_hugetlb(test_case->fn, test_case->desc,
>> @@ -1671,7 +1681,7 @@ static int tests_per_non_anon_test_case(void)
>> {
>> int tests = 3 + nr_hugetlbsizes;
>>
>> - if (thpsize)
>> + if (pmdsize)
>> tests += 1;
>> return tests;
>> }
>> @@ -1681,10 +1691,13 @@ int main(int argc, char **argv)
>> int err;
>>
>> pagesize = getpagesize();
>> - thpsize = read_pmd_pagesize();
>> - if (thpsize)
>> + pmdsize = read_pmd_pagesize();
>> + if (pmdsize) {
>> + ksft_print_msg("[INFO] detected PMD size: %zu KiB\n",
>> + pmdsize / 1024);
>> ksft_print_msg("[INFO] detected THP size: %zu KiB\n",
>> - thpsize / 1024);
>> + pmdsize / 1024);
>> + }
>> nr_hugetlbsizes = detect_hugetlb_page_sizes(hugetlbsizes,
>> ARRAY_SIZE(hugetlbsizes));
>> detect_huge_zeropage();
>> --
>> 2.25.1
>>