Re: [PATCH v3 5/6] userfaultfd: selftests: make /dev/userfaultfd testing configurable

On Wed, Jun 01, 2022 at 02:09:50PM -0700, Axel Rasmussen wrote:

Instead of always testing both userfaultfd(2) and /dev/userfaultfd, let the user choose which to test.

As with other test features, change the behavior based on a new command line flag. Introduce the idea of "test mods", which are generic (not specific to a test type) modifications to the behavior of the test. This is sort of borrowed from this RFC patch series [1], but simplified a bit.

The benefit is, in "typical" configurations this test is somewhat slow (say, 30sec or something). Testing both clearly doubles it, so it may not always be desirable, as users are likely to use one or the other, but never both, in the "real world".

Yes, when I was reading your other patch I was wishing no timeout of any of QE testbeds could trigger.

If you plan to remove it anyway, mind to squash these?

Signed-off-by: Axel Rasmussen axelrasmussen@google.com

tools/testing/selftests/vm/userfaultfd.c | 41 +++++++++++++++++------- 1 file changed, 30 insertions(+), 11 deletions(-)

diff --git a/tools/testing/selftests/vm/userfaultfd.c b/tools/testing/selftests/vm/userfaultfd.c index 1badb5d31bf9..aeee6f1ad8ef 100644 --- a/tools/testing/selftests/vm/userfaultfd.c +++ b/tools/testing/selftests/vm/userfaultfd.c @@ -128,6 +128,8 @@ struct uffd_stats { const char *examples = "# Run anonymous memory test on 100MiB region with 99999 bounces:\n" "./userfaultfd anon 100 99999\n\n"

• "# Run the same anonymous memory test, but using /dev/userfaultfd:\n"
• "./userfaultfd anon:dev 100 99999\n\n" "# Run share memory test on 1GiB region with 99 bounces:\n" "./userfaultfd shmem 1000 99\n\n" "# Run hugetlb memory test on 256MiB region with 50 bounces:\n"

@@ -144,6 +146,13 @@ static void usage(void) "[hugetlbfs_file]\n\n"); fprintf(stderr, "Supported <test type>: anon, hugetlb, " "hugetlb_shared, shmem\n\n");

• fprintf(stderr, "'Test mods' can be joined to the test type string with a ':'. "

• "Supported mods:\n");
  

• fprintf(stderr, "\tdev - Use /dev/userfaultfd instead of userfaultfd(2)\n");

That looks better than running everything by default twice. Though let's also provide "syscall" if we're at it, anyway?

Thanks,

• fprintf(stderr, "\nExample test mod usage:\n");
• fprintf(stderr, "# Run anonymous memory test with /dev/userfaultfd:\n");
• fprintf(stderr, "./userfaultfd anon:dev 100 99999\n\n");
• fprintf(stderr, "Examples:\n\n"); fprintf(stderr, "%s", examples); exit(1);

@@ -1607,8 +1616,6 @@ unsigned long default_huge_page_size(void) static void set_test_type(const char *type) {

• uint64_t features = UFFD_API_FEATURES;
• if (!strcmp(type, "anon")) { test_type = TEST_ANON; uffd_test_ops = &anon_uffd_test_ops;

@@ -1626,10 +1633,28 @@ static void set_test_type(const char *type) test_type = TEST_SHMEM; uffd_test_ops = &shmem_uffd_test_ops; test_uffdio_minor = true;

• } else {

• err("Unknown test type: %s", type);
  

• }

+}

+static void parse_test_type_arg(const char *raw_type) +{

• char *buf = strdup(raw_type);
• uint64_t features = UFFD_API_FEATURES;
• while (buf) {

• const char *token = strsep(&buf, ":");
  

• if (!test_type)
  

• 	set_test_type(token);
  

• else if (!strcmp(token, "dev"))
  

• 	test_dev_userfaultfd = true;
  

• else
  

• 	err("unrecognized test mod '%s'", token);
  

  }

• if (!test_type)

• err("failed to parse test type argument: '%s'", raw_type);
  

• if (test_type == TEST_HUGETLB) page_size = default_huge_page_size(); else

@@ -1676,7 +1701,7 @@ int main(int argc, char **argv) err("failed to arm SIGALRM"); alarm(ALARM_INTERVAL_SECS);

• set_test_type(argv[1]);

• parse_test_type_arg(argv[1]);

nr_cpus = sysconf(_SC_NPROCESSORS_ONLN); nr_pages_per_cpu = atol(argv[2]) * 1024*1024 / page_size / @@ -1714,12 +1739,6 @@ int main(int argc, char **argv) } printf("nr_pages: %lu, nr_pages_per_cpu: %lu\n", nr_pages, nr_pages_per_cpu);

• test_dev_userfaultfd = false;
• if (userfaultfd_stress())

• return 1;
  

• test_dev_userfaultfd = true; return userfaultfd_stress();

} -- 2.36.1.255.ge46751e96f-goog