Hi Mike!
On 5/20/26 2:25 PM, Mike Rapoport wrote:
> (added broonie)
>
> Hi,
>
> On Tue, May 19, 2026 at 05:35:05PM +0530, Sarthak Sharma wrote:
>> Add a command-line tool for benchmarking get_user_pages fast-path
>> (GUP_FAST), pin_user_pages fast-path (PIN_FAST), and pin_user_pages
>> longterm (PIN_LONGTERM) via the CONFIG_GUP_TEST debugfs interface.
>>
>> When invoked without arguments, gup_bench runs the same matrix of
>> configurations as run_gup_matrix() in run_vmtests.sh: all three GUP
>> commands across read/write, private/shared mappings, and a range of
>> page counts, with THP on/off for regular mappings and hugetlb for huge
>> page mappings.
>>
>> This tool is a mix of reused and new logic. The mapping/setup path comes
>> from selftests/mm/gup_test.c, while the default benchmark matrix matches
>> run_gup_matrix() in run_vmtests.sh. The standalone CLI and tools/mm
>> integration are added here so tools/mm does not depend on kselftest.
>>
>> Add gup_bench to BUILD_TARGETS and INSTALL_TARGETS in tools/mm/Makefile,
>> and ignore the resulting binary in tools/mm/.gitignore. While here, also
>> add the missing thp_swap_allocator_test entry to .gitignore.
>>
>> Add tools/mm/gup_bench.c to the GUP entry in MAINTAINERS.
>>
>> Suggested-by: David Hildenbrand (Arm) <[email protected]>
>> Signed-off-by: Sarthak Sharma <[email protected]>
>> ---
>> MAINTAINERS | 1 +
>> tools/mm/.gitignore | 2 +
>> tools/mm/Makefile | 6 +-
>> tools/mm/gup_bench.c | 491 +++++++++++++++++++++++++++++++++++++++++++
>> 4 files changed, 497 insertions(+), 3 deletions(-)
>> create mode 100644 tools/mm/gup_bench.c
>
> ...
>
>> +/*
>> + * Local HugeTLB setup helpers for gup_bench.
>> + *
>> + * These helpers were copied from tools/testing/selftests/mm/ and adjusted
>> to
>> + * remove the ksft formatting. Keep this copy local so tools/mm does not
>> + * depend on ksft output behavior.
>> + */
>
> It looks like self tests of at least 5 subsystems beside mm use hugetlb:
>
> $ git grep -l "Hugepagesize:" tools/testing/selftests/ | grep -v
> "selftests/mm"
> tools/testing/selftests/arm64/mte/check_hugetlb_options.c
> tools/testing/selftests/cgroup/test_hugetlb_memcg.c
> tools/testing/selftests/kvm/lib/test_util.c
> tools/testing/selftests/memfd/common.c
> tools/testing/selftests/net/tcp_mmap.c
>
> It seems that we need to better share the common code in
> tools/testing/selftest.
>
> And adding another copy of the hugetlb detection and setup code does not
> seem like a great idea.
Agreed, but that was the least disruptive approach I could think of.
I am thinking of doing this now: should I move the
hugepage_settings.[ch] to tools/lib/ and move the read_num(),
write_num(), read_file() and write_file() helpers to a separate file in
tools/lib/ itself without any ksft dependency? Then both
tools/testing/selftests/* and tools/mm/ could share the same code.
Please let me know if some different approach is preferred.
>
>> +
>> +static unsigned int psize(void)
>> +{
>> + static unsigned int __page_size;
>> +
>> + if (!__page_size)
>> + __page_size = sysconf(_SC_PAGESIZE);
>> + return __page_size;
>> +}
>> +
>> +static unsigned long default_huge_page_size(void)
>> +{
>> + FILE *f = fopen("/proc/meminfo", "r");
>> + unsigned long hpage_size = 0;
>> + char buf[256];
>> +
>> + if (!f)
>> + return 0;
>> + while (fgets(buf, sizeof(buf), f)) {
>> + if (sscanf(buf, "Hugepagesize: %lu kB", &hpage_size) == 1)
>> + break;
>> + }
>> + fclose(f);
>> + hpage_size <<= 10;
>> + return hpage_size;
>> +}
>
