linux-kernel - Re: [PATCH] kunit: time: Add faster unit test with shorter time range

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Date: Thu, 14 Mar 2024 15:05:03 -0400
From: Rae Moar <rmoar@...gle.com>
To: Guenter Roeck <linux@...ck-us.net>
Cc: John Stultz <jstultz@...gle.com>, Thomas Gleixner <tglx@...utronix.de>, 
	Stephen Boyd <sboyd@...nel.org>, linux-kernel@...r.kernel.org, 
	Daniel Diaz <daniel.diaz@...aro.org>, Shuah Khan <skhan@...uxfoundation.org>
Subject: Re: [PATCH] kunit: time: Add faster unit test with shorter time range

On Wed, Mar 13, 2024 at 5:01 PM Guenter Roeck <linux@...ck-us.net> wrote:
>
> Commit a547c4ce10bd ("kunit: time: Mark test as slow using test
> attributes") marked the time unit test as slow. This means it does not
> run anymore if slow tests are disabled. This reduces test coverage and
> is thus undesirable. At the same time, the test currently covers a range
> of 160,000 years, which has limited value.
>
> Add additional test case covering a total range of 1,600 years. This test
> takes less than a second to run even on slow systems while still covering
> twice the leap year calculation range of 400 years around the center date.
> This test can run even with slow tests disabled.

Hello!

I really like this addition of another time range test. This looks good to me.

Thanks!
-Rae

Reviewed-by: Rae Moar <rmoar@...gle.com>

>
> Cc: Rae Moar <rmoar@...gle.com>
> Cc: Shuah Khan <skhan@...uxfoundation.org>
> Signed-off-by: Guenter Roeck <linux@...ck-us.net>
> ---
>  kernel/time/time_test.c | 35 +++++++++++++++++++++++++++--------
>  1 file changed, 27 insertions(+), 8 deletions(-)
>
> diff --git a/kernel/time/time_test.c b/kernel/time/time_test.c
> index 3e5d422dd15c..15c6f3a5e73c 100644
> --- a/kernel/time/time_test.c
> +++ b/kernel/time/time_test.c
> @@ -47,18 +47,18 @@ static void advance_date(long *year, int *month, int *mday, int *yday)
>  }
>
>  /*
> - * Checks every day in a 160000 years interval centered at 1970-01-01
> + * Checks every day in a specified interval centered at 1970-01-01
>   * against the expected result.
>   */
> -static void time64_to_tm_test_date_range(struct kunit *test)
> +static void time64_to_tm_test_date_range(struct kunit *test, int years)
>  {
>         /*
> -        * 80000 years  = (80000 / 400) * 400 years
> -        *              = (80000 / 400) * 146097 days
> -        *              = (80000 / 400) * 146097 * 86400 seconds
> +        * years        = (years / 400) * 400 years

This is tiny but if there is another version, I find this comment a
bit confusing. Could you change this to maybe be "total seconds ="
instead of "years =" because years is used as a unit on the right side
of the equation?

> +        *              = (years / 400) * 146097 days
> +        *              = (years / 400) * 146097 * 86400 seconds
>          */
> -       time64_t total_secs = ((time64_t) 80000) / 400 * 146097 * 86400;
> -       long year = 1970 - 80000;
> +       time64_t total_secs = ((time64_t) years) / 400 * 146097 * 86400;
> +       long year = 1970 - years;
>         int month = 1;
>         int mdday = 1;
>         int yday = 0;
> @@ -85,8 +85,27 @@ static void time64_to_tm_test_date_range(struct kunit *test)
>         }
>  }
>
> + /*
> +  * Checks every day in a 1600 years interval centered at 1970-01-01
> +  * against the expected result.
> +  */
> +static void time64_to_tm_test_date_range_1600(struct kunit *test)
> +{
> +       time64_to_tm_test_date_range(test, 800);
> +}
> +
> + /*
> +  * Checks every day in a 160000 years interval centered at 1970-01-01
> +  * against the expected result.
> +  */
> +static void time64_to_tm_test_date_range_160000(struct kunit *test)
> +{
> +       time64_to_tm_test_date_range(test, 80000);
> +}
> +
>  static struct kunit_case time_test_cases[] = {
> -       KUNIT_CASE_SLOW(time64_to_tm_test_date_range),
> +       KUNIT_CASE(time64_to_tm_test_date_range_1600),
> +       KUNIT_CASE_SLOW(time64_to_tm_test_date_range_160000),
>         {}
>  };
>
> --
> 2.39.2
>