Re: [PATCH v2 5/7] migration/multifd: Add new migration test cases for legacy zero page checking.

[Fabiano Rosas <farosas@suse.de>]

Hao Xiang <hao.xiang@bytedance.com> writes:

> Now that zero page checking is done on the multifd sender threads by
> default, we still provide an option for backward compatibility. This
> change adds a qtest migration test case to set the zero-page-detection
> option to "legacy" and run multifd migration with zero page checking on the
> migration main thread.
>
> Signed-off-by: Hao Xiang <hao.xiang@bytedance.com>
> ---
>  tests/qtest/migration-test.c | 52 ++++++++++++++++++++++++++++++++++++
>  1 file changed, 52 insertions(+)
>
> diff --git a/tests/qtest/migration-test.c b/tests/qtest/migration-test.c
> index 8a5bb1752e..c27083110a 100644
> --- a/tests/qtest/migration-test.c
> +++ b/tests/qtest/migration-test.c
> @@ -2621,6 +2621,24 @@ test_migrate_precopy_tcp_multifd_start(QTestState *from,
>      return test_migrate_precopy_tcp_multifd_start_common(from, to, "none");
>  }
>  
> +static void *
> +test_migrate_precopy_tcp_multifd_start_zero_page_legacy(QTestState *from,
> +                                                        QTestState *to)
> +{
> +    test_migrate_precopy_tcp_multifd_start_common(from, to, "none");
> +    migrate_set_parameter_str(from, "zero-page-detection", "legacy");
> +    return NULL;
> +}
> +
> +static void *
> +test_migration_precopy_tcp_multifd_start_no_zero_page(QTestState *from,
> +                                                      QTestState *to)
> +{
> +    test_migrate_precopy_tcp_multifd_start_common(from, to, "none");
> +    migrate_set_parameter_str(from, "zero-page-detection", "none");
> +    return NULL;
> +}
> +
>  static void *
>  test_migrate_precopy_tcp_multifd_zlib_start(QTestState *from,
>                                              QTestState *to)
> @@ -2652,6 +2670,36 @@ static void test_multifd_tcp_none(void)
>      test_precopy_common(&args);
>  }
>  
> +static void test_multifd_tcp_zero_page_legacy(void)
> +{
> +    MigrateCommon args = {
> +        .listen_uri = "defer",
> +        .start_hook = test_migrate_precopy_tcp_multifd_start_zero_page_legacy,
> +        /*
> +         * Multifd is more complicated than most of the features, it
> +         * directly takes guest page buffers when sending, make sure
> +         * everything will work alright even if guest page is changing.
> +         */
> +        .live = true,
> +    };
> +    test_precopy_common(&args);
> +}
> +
> +static void test_multifd_tcp_no_zero_page(void)
> +{
> +    MigrateCommon args = {
> +        .listen_uri = "defer",
> +        .start_hook = test_migration_precopy_tcp_multifd_start_no_zero_page,
> +        /*
> +         * Multifd is more complicated than most of the features, it
> +         * directly takes guest page buffers when sending, make sure
> +         * everything will work alright even if guest page is changing.
> +         */
> +        .live = true,
> +    };
> +    test_precopy_common(&args);
> +}
> +
>  static void test_multifd_tcp_zlib(void)
>  {
>      MigrateCommon args = {
> @@ -3550,6 +3598,10 @@ int main(int argc, char **argv)
>      }
>      migration_test_add("/migration/multifd/tcp/plain/none",
>                         test_multifd_tcp_none);
> +    migration_test_add("/migration/multifd/tcp/plain/zero_page_legacy",
> +                       test_multifd_tcp_zero_page_legacy);
> +    migration_test_add("/migration/multifd/tcp/plain/no_zero_page",
> +                       test_multifd_tcp_no_zero_page);

Here it's better to separate the main feature from the states. That way
we can run only the zero-page tests with:

 migration-test -r /x86_64/migration/multifd/tcp/plain/zero-page

Like so: (also dashes instead of underscores)
/zero-page/legacy
/zero-page/none

>      migration_test_add("/migration/multifd/tcp/plain/cancel",
>                         test_multifd_tcp_cancel);
>      migration_test_add("/migration/multifd/tcp/plain/zlib",