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Message-ID: <YqjkyFIgPSuXK+dz@xz-m1.local>
Date: Tue, 14 Jun 2022 15:43:04 -0400
From: Peter Xu <peterx@...hat.com>
To: Axel Rasmussen <axelrasmussen@...gle.com>
Cc: Alexander Viro <viro@...iv.linux.org.uk>,
Andrew Morton <akpm@...ux-foundation.org>,
Charan Teja Reddy <charante@...eaurora.org>,
Dave Hansen <dave.hansen@...ux.intel.com>,
"Dmitry V . Levin" <ldv@...linux.org>,
Gleb Fotengauer-Malinovskiy <glebfm@...linux.org>,
Hugh Dickins <hughd@...gle.com>, Jan Kara <jack@...e.cz>,
Jonathan Corbet <corbet@....net>,
Mel Gorman <mgorman@...hsingularity.net>,
Mike Kravetz <mike.kravetz@...cle.com>,
Mike Rapoport <rppt@...nel.org>, Nadav Amit <namit@...are.com>,
Shuah Khan <shuah@...nel.org>,
Suren Baghdasaryan <surenb@...gle.com>,
Vlastimil Babka <vbabka@...e.cz>,
zhangyi <yi.zhang@...wei.com>, linux-doc@...r.kernel.org,
linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-mm@...ck.org, linux-kselftest@...r.kernel.org
Subject: 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?
>
> [1]: https://patchwork.kernel.org/project/linux-mm/patch/20201129004548.1619714-14-namit@vmware.com/
>
> Signed-off-by: Axel Rasmussen <axelrasmussen@...gle.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
>
--
Peter Xu
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