Re: [libevl][PATCH 1/4] Copy dohell from Xenomai 3

[Philippe Gerum <rpm@xenomai.org>]

Jan Kiszka <jan.kiszka@siemens.com> writes:

> On 13.06.24 16:23, Philippe Gerum wrote:
>> 
>> Tobias Schaffner <tobias.schaffner@siemens.com> writes:
>> 
>>> Dohell is used as the default load generator in Xenomai 3. Add it to
>>> libevl to be able to stress the system while testing evl.
>>>
>> 
>> dohell is obsolete. Let's move to stress-ng or something alike for x4.
>> 
>
> See my comment on patch 3: If you can name a configuration of stress-ng
> that stresses a co-kernel more than what dohell does, we can take it.
> Otherwise, I would strongly recommend to not do less hell over here.
>

The most important stress dohell applies is basically hackbench and a dd
loop trashing the D-cache. The latter can be obtained with a combo of
VM+I/O tests from stress-ng. So basically, the whole issue boils down to
having hackbench on board, provided we cannot generate the same load
profile with stress-ng with a CPU bound stressor. Besides, I never saw
any added value in running ltp tests compared to a combo of stress-ng
stressors when it comes to latency testing.

We obviously don't want to throw less hell, but throwing more obsolete
stuff is not an option either. So that's a NAK for v4 ATM, I'll gather
more information about how we could leverage stress-ng in order to
compare to dohell. This is worth a shot.

-- 
Philippe.