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Message-ID: <8dd0f52c-d261-4541-930f-bd4e5921be5b@arm.com>
Date: Mon, 27 Nov 2023 14:02:04 +0000
From: Ryan Roberts <ryan.roberts@....com>
To: Andrew Morton <akpm@...ux-foundation.org>,
Matthew Wilcox <willy@...radead.org>,
Yin Fengwei <fengwei.yin@...el.com>,
David Hildenbrand <david@...hat.com>,
Yu Zhao <yuzhao@...gle.com>,
Catalin Marinas <catalin.marinas@....com>,
Anshuman Khandual <anshuman.khandual@....com>,
Yang Shi <shy828301@...il.com>,
"Huang, Ying" <ying.huang@...el.com>, Zi Yan <ziy@...dia.com>,
Luis Chamberlain <mcgrof@...nel.org>,
Itaru Kitayama <itaru.kitayama@...il.com>,
"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
John Hubbard <jhubbard@...dia.com>,
David Rientjes <rientjes@...gle.com>,
Vlastimil Babka <vbabka@...e.cz>,
Hugh Dickins <hughd@...gle.com>,
Kefeng Wang <wangkefeng.wang@...wei.com>
Cc: linux-mm@...ck.org, linux-arm-kernel@...ts.infradead.org,
linux-kernel@...r.kernel.org
Subject: Re: [RESEND PATCH v7 10/10] selftests/mm/cow: Add tests for anonymous
small-sized THP
On 22/11/2023 16:29, Ryan Roberts wrote:
> Add tests similar to the existing PMD-sized THP tests, but which operate
> on memory backed by (PTE-mapped) small-sized THP. This reuses all the
> existing infrastructure. If the test suite detects that small-sized THP
> is not supported by the kernel, the new tests are skipped.
>
> Signed-off-by: Ryan Roberts <ryan.roberts@....com>
> ---
> tools/testing/selftests/mm/cow.c | 71 +++++++++++++++++++++++++++++++-
> 1 file changed, 70 insertions(+), 1 deletion(-)
>
> diff --git a/tools/testing/selftests/mm/cow.c b/tools/testing/selftests/mm/cow.c
> index d03c453cfd5c..3efc395c7077 100644
> --- a/tools/testing/selftests/mm/cow.c
> +++ b/tools/testing/selftests/mm/cow.c
> @@ -29,15 +29,49 @@
> #include "../../../../mm/gup_test.h"
> #include "../kselftest.h"
> #include "vm_util.h"
> +#include "thp_settings.h"
>
> static size_t pagesize;
> static int pagemap_fd;
> static size_t pmdsize;
> +static int nr_thpsmallsizes;
> +static size_t thpsmallsizes[20];
Off the back of some comments David made againt the previous patch [1], I'm
proposing to rework this a bit so that ALL thp sizes are stored in this array,
not just the non-PMD-sized sizes. This makes the changes overall a bit smaller
and easier to understand, I think...
> static int nr_hugetlbsizes;
> static size_t hugetlbsizes[10];
> static int gup_fd;
> static bool has_huge_zeropage;
>
> +static int sz2ord(size_t size)
> +{
> + return __builtin_ctzll(size / pagesize);
> +}
> +
> +static int detect_smallthp_sizes(size_t sizes[], int max)
This changes to detect_thp_sizes() and deposits all sizes in sizes[]
> +{
> + int count = 0;
> + unsigned long orders;
> + size_t kb;
> + int i;
> +
> + /* thp not supported at all. */
> + if (!pmdsize)
> + return 0;
> +
> + orders = thp_supported_orders();
> +
> + /* Only interested in small-sized THP (less than PMD-size). */
> + for (i = 0; i < sz2ord(pmdsize); i++) {
> + if (!(orders & (1UL << i)))
> + continue;
> + kb = (pagesize >> 10) << i;
> + sizes[count++] = kb * 1024;
> + ksft_print_msg("[INFO] detected small-sized THP size: %zu KiB\n",
> + kb);
This just prints "[INFO] detected THP size: %zu KiB"
> + }
> +
> + return count;
> +}
> +
> static void detect_huge_zeropage(void)
> {
> int fd = open("/sys/kernel/mm/transparent_hugepage/use_zero_page",
> @@ -1113,6 +1147,23 @@ static void run_anon_test_case(struct test_case const *test_case)
> 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_thpsmallsizes; i++) {
> + size_t size = thpsmallsizes[i];
> + struct thp_settings settings = *thp_current_settings();
> +
> + settings.hugepages[sz2ord(pmdsize)].enabled = THP_NEVER;
> + settings.hugepages[sz2ord(size)].enabled = THP_ALWAYS;
> + thp_push_settings(&settings);
> +
> + run_with_pte_mapped_thp(test_case->fn, test_case->desc, size);
> + run_with_pte_mapped_thp_swap(test_case->fn, test_case->desc, size);
> + run_with_single_pte_of_thp(test_case->fn, test_case->desc, size);
> + run_with_single_pte_of_thp_swap(test_case->fn, test_case->desc, size);
> + run_with_partial_mremap_thp(test_case->fn, test_case->desc, size);
> + run_with_partial_shared_thp(test_case->fn, test_case->desc, size);
> +
> + thp_pop_settings();
> + }
This same loop covers the pmdsize tests too, and I've just added a conditional
that runs the 2 extra tests that are pmdsize only.
> for (i = 0; i < nr_hugetlbsizes; i++)
> run_with_hugetlb(test_case->fn, test_case->desc,
> hugetlbsizes[i]);
> @@ -1134,6 +1185,7 @@ static int tests_per_anon_test_case(void)
>
> if (pmdsize)
> tests += 8;
> + tests += 6 * nr_thpsmallsizes;
> return tests;
> }
>
> @@ -1691,12 +1743,24 @@ static int tests_per_non_anon_test_case(void)
> int main(int argc, char **argv)
> {
> int err;
> + struct thp_settings default_settings;
>
> pagesize = getpagesize();
> pmdsize = read_pmd_pagesize();
> - if (pmdsize)
> + if (pmdsize) {
> + /* Only if THP is supported. */
> + thp_read_settings(&default_settings);
> + default_settings.hugepages[sz2ord(pmdsize)].enabled = THP_GLOBAL;
> + thp_save_settings();
> + thp_push_settings(&default_settings);
> +
> ksft_print_msg("[INFO] detected PMD-mapped THP size: %zu KiB\n",
> pmdsize / 1024);
> +
> + nr_thpsmallsizes = detect_smallthp_sizes(thpsmallsizes,
> + ARRAY_SIZE(thpsmallsizes));
> + }
> +
> nr_hugetlbsizes = detect_hugetlb_page_sizes(hugetlbsizes,
> ARRAY_SIZE(hugetlbsizes));
> detect_huge_zeropage();
> @@ -1715,6 +1779,11 @@ int main(int argc, char **argv)
> run_anon_thp_test_cases();
> run_non_anon_test_cases();
>
> + if (pmdsize) {
> + /* Only if THP is supported. */
> + thp_restore_settings();
> + }
> +
> err = ksft_get_fail_cnt();
> if (err)
> ksft_exit_fail_msg("%d out of %d tests failed\n",
> --
> 2.25.1
>
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