[LTP] [PATCH 1/2] setitimer01: add interval timer test

[Li Wang]

On Tue, Nov 15, 2022 at 6:00 PM Li Wang <liwang@redhat.com> wrote:

> Richard Palethorpe <rpalethorpe@suse.de> wrote:
>
>
>> >
>> >  Practically speaking we have to assume a large amount of time has
>> passed
>> >  when using ITIMER_REAL. It has to be *much* larger than a VM is likely
>> >  to be paused for and then successfully resumed. Or the amount of time a
>> >  clock may be corrected by (for e.g. with NTP).
>> >
>> > Hmm, not sure if I understand correctly above, will that
>> > timer value be out of the range but reasonable?
>> >
>> > Or is there any additional situation we should cover?
>>
>> Sorry that is confusing.
>>
>> The question is what happens if the clock jumps backwards?
>>
>> I don't see anything which says it_value.tv_sec can't go out of
>> range. OTOH I would expect it to compensate for large jumps in time.
>>
>> If the test randomly fails because it_value.tv_sec > time_sec then what
>> action will we take?
>>
>
Or, we do nothing on this, just let the test report TFAIL, because that
is not what this test can control.



>
> How about increasing the time_sec on virtual machine?
>
> Seems no perfect way to completely resolve but only reducing
> the odds of happening.
>
> Or do you have another better suggestion?
>
> --- a/testcases/kernel/syscalls/setitimer/setitimer01.c
> +++ b/testcases/kernel/syscalls/setitimer/setitimer01.c
> @@ -142,6 +142,11 @@ static void setup(void)
>
>         time_sec  = 9 + time_step / 1000;
>         time_usec = 3 * time_step;
> +
> +       if (tst_is_virt(VIRT_ANY)) {
> +               tst_res(TINFO, "Running in a VM, multiply the time_sec by
> 10.");
> +               time_sec *= 10;
> +       }
>  }
>
>
> --
> Regards,
> Li Wang
>


-- 
Regards,
Li Wang
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.linux.it/pipermail/ltp/attachments/20221115/9949f4ad/attachment.htm>