Re: rte_service unit test failing randomly

["Mattias Rönnblom" <mattias.ronnblom@ericsson.com>]

On 2022-10-06 10:18, Morten Brørup wrote:
>> From: Mattias Rönnblom [mailto:mattias.ronnblom@ericsson.com]
>> Sent: Thursday, 6 October 2022 09.51
>>
>> On 2022-10-06 08:53, Morten Brørup wrote:
> 
> [...]
> 
>>> I have been wondering how accurate the tests really are. Where can I
>> see what is being done to ensure that the EAL worker threads are fully
>> isolated, and never interrupted by the O/S scheduler or similar?
>>>
>>
>> There are kernel-level counters for how many times a thread have been
>> involuntarily interrupted,
> 
> Thanks, Mattias. I will look into that.
> 
> Old kernels (2.4 and 2.6) ascribed the time spent in interrupt handlers to the CPU usage of the running process, instead of counting the time spent in interrupt handlers separately. Does anyone know it this has been fixed?
> 

If you mean top half interrupt handler, my guess would be it does not 
matter, except in some strange corner cases or faulty hardware. An ISR 
should have very short run time, and not being run *that* often (after 
NAPI). With isolated cores, it should be even less of a problem, but 
then you may not have that.

Bottom halves are not attributed to the process, I believe. (In old 
kernels, the time spent in soft IRQs were not attributed to anything, 
which could create situations where the system was very busy indeed 
[e.g., with network stack bottom halves doing IP forwarding], but 
looking idle in 'top'.)

>> and also, if I recall correctly, the amount
>> of wall-time the thread have been runnable, but not running (i.e.,
>> waiting to be scheduled). The latter may require some scheduler debug
>> kernel option being enabled on the kernel build.
> 
>