Re: [LTP] [PATCH 1/2] lib: multiply the timeout if detect slow kconfigs

[Petr Vorel <pvorel@suse.cz>]

Hi Li, all,

[ Cc others to get broather feedback ]

> This refines the handling of timeouts for tests running on
> systems with slow kernel configurations (kconfigs).

> Previously, the max_runtime was multiplied globally when
> slow kconfigs were detected, which inadvertently prolonged
> the runtime of all tests using max_runtime for control.

> This patch corrects that behavior by applying the multiplication
> specifically to timeouts, ensuring it only affects the intended
> operations without impacting other tests.

> Fixes: 2da30df24 ("lib: multiply the max_runtime if detect slow kconfigs")

Thanks for handling this, I overlooked it on 27th, thus review it now.

Multiplying whole timeout instead of max_runtime helps to hide longer timeout
from the test which uses detection via tst_remaining_runtime(). I.e. previously
it behaved on slow config as LTP_RUNTIME_MUL=4, now as LTP_TIMEOUT_MUL=4.
Good idea. IMHO good enough (Martin previously suggested [1] to add a new
tst_test flag to identify tests which exit when runtime expires).

Reviewed-by: Petr Vorel <pvorel@suse.cz>

Some measurements on my Tumbleweed VM, which is detected as slow due CONFIG_LATENCYTOP:

TEST                                              | 2da30df24~ | 2da30df24  | this patch
--------------------------------------------------|-------------------------------------
swapping01.c (calls tst_remaining_runtime())      | 0h 10m 30s | 0h 40m 30s | 0h 12m 00s
tst_fuzzy_sync01.c (calls tst_remaining_runtime())| 0h 03m 00s | 0h 10m 30s | 0h 04m 30s
tst_cgroup02.c (default timeout 0h 00m 30s)       | 0h 00m 30s | 0h 00m 30s | 0h 02m 00s
test_runtime01.c (.max_runtime = 4, calls         | 0h 00m 34s | 0h 00m 46s | 0h 02m 04s
tst_remaining_runtime())
starvation.c (calls tst_remaining_runtime() only  | 0h 01m 05s | 0h 02m 50s | 0h 02m 34s
to detect failure)                                |

=> Tests which call tst_remaining_runtime() runs slightly longer, but IMHO
that's OK. Other tests (regardless if with the default runtime or these which
set .max_runtime) run 4* longer as expected.

Tested-by: Petr Vorel <pvorel@suse.cz>

Kind regards,
Petr

[1] https://lore.kernel.org/ltp/b6da77f3-45d6-4eed-b2d3-90ad20c63e50@suse.cz/

> Signed-off-by: Li Wang <liwang@redhat.com>
> ---
>  lib/tst_test.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)

> diff --git a/lib/tst_test.c b/lib/tst_test.c
> index 205fc8326..feffc9f86 100644
> --- a/lib/tst_test.c
> +++ b/lib/tst_test.c
> @@ -555,9 +555,6 @@ static int multiply_runtime(int max_runtime)

>  	parse_mul(&runtime_mul, "LTP_RUNTIME_MUL", 0.0099, 100);

> -	if (tst_has_slow_kconfig())
> -		max_runtime *= 4;
> -
>  	return max_runtime * runtime_mul;
>  }

> @@ -1706,6 +1703,9 @@ unsigned int tst_multiply_timeout(unsigned int timeout)
>  	if (timeout < 1)
>  		tst_brk(TBROK, "timeout must to be >= 1! (%d)", timeout);

> +	if (tst_has_slow_kconfig())
> +		timeout *= 4;
> +
>  	return timeout * timeout_mul;
>  }

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