Re: [PATCH xenomai-images] ci: do not skip tests on vm that have been relaxed

On 03.07.26 16:00, Tobias Schaffner wrote:
> 
> 
> On 7/3/26 14:07, Jan Kiszka wrote:
>> On 03.07.26 13:54, Tobias Schaffner wrote:
>>> Hi all,
>>>
>>> in some of my test runs the sched-tp-overrun test was failing with:
>>> 2026-06-23T17:25:44 ../tests/sched-tp-overrun.c:119: FAILED:
>>> evl_read_observable(tfd, &nf, 1) (=Resource temporarily unavailable)
>>> 2026-06-23T17:25:44 ** sched-tp-overrun: BROKEN
>>>
>>> I only see this on virtual targets.
>>> e.g.: https://code.siemens.com/ebsy/debian/xenomai-images/-/
>>> jobs/393605372
>>> Mostly on arm but also saw this on qemu-amd64 in one of my recent runs.
>>>
>>
>> Maybe improper/missing synchronization during test startup? Or when is
>> this hit?
> 
> 
> Does not look like a synchronization problem to me.
> The key part of the test failure is this combination:
> 
> /*
> * Trigger an overrun condition by staying busy for longer
> * than the duration of our allotted time window.
> */
> for (;;) {
>     evl_read_clock(EVL_CLOCK_MONOTONIC, &now);
>     if (timespec_sub_ns(&now, &start) > OVERRUN_TIME)
>         break;
> }
> 
> /*
> * Now check whether we received the overrun event as
> * expected. Since non-blocking input is enabled, a lack of
> * notification would amount to an error (EAGAIN).
> */
> __Tcall_assert(ret, evl_read_observable(tfd, &nf, 1));
> 
> 
> The OVERRUN_TIME of 200us seems to be not enough to trigger the overrun
> or in some cases or at least the message was not send in time.
> 
> I suspected the issue to be time stealing but saw the fixup parts of the
> tp scheduler trying to handle missed time frames. I think we just have
> to increase the overrun time but not sure how much to still keep the
> fixup parts tested. I guess these code paths are only exercised on
> virtual targets.
> 

So, do you want to drop tp-overrun from this patch for now, or how to
proceed?

Jan

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