Re: [PATCH v2 3/5] automation: Add the expect script with test case for FVP

[Michal Orzel <michal.orzel@xxxxxxx>]

On 08/12/2023 10:21, Henry Wang wrote:
> 
> 
> Hi Michal,
> 
>> On Dec 8, 2023, at 17:11, Michal Orzel <michal.orzel@xxxxxxx> wrote:
>> On 08/12/2023 10:05, Henry Wang wrote:
>>>
>>> Hi Michal,
>>>
>>>> On Dec 8, 2023, at 16:57, Michal Orzel <michal.orzel@xxxxxxx> wrote:
>>>>
>>>> Hi Henry,
>>>>
>>>> On 08/12/2023 06:46, Henry Wang wrote:
>>>>> diff --git a/automation/scripts/expect/fvp-base-smoke-dom0-arm64.exp 
>>>>> b/automation/scripts/expect/fvp-base-smoke-dom0-arm64.exp
>>>>> new file mode 100755
>>>>> index 0000000000..25d9a5f81c
>>>>> --- /dev/null
>>>>> +++ b/automation/scripts/expect/fvp-base-smoke-dom0-arm64.exp
>>>>> @@ -0,0 +1,73 @@
>>>>> +#!/usr/bin/expect
>>>>> +
>>>>> +set timeout 2000
>>>> Do we really need such a big timeout (~30 min)?
>>>> Looking at your test job, it took 16 mins (quite a lot but I know FVP is 
>>>> slow
>>>> + send_slow slows things down)
>>>
>>> This is a really good question. I did have the same question while working 
>>> on
>>> the negative test today. The timeout 2000 indeed will fail the job at about 
>>> 30min,
>>> and waiting for it is indeed not really pleasant.
>>>
>>> But my second thought would be - from my observation, the overall time now
>>> would vary between 15min ~ 20min, and having a 10min margin is not that 
>>> crazy
>>> given that we probably will do more testing from the job in the future, and 
>>> if the
>>> GitLab Arm worker is high loaded, FVP will probably become slower. And 
>>> normally
>>> we don’t even trigger the timeout as the job will normally pass. So I 
>>> decided
>>> to keep this.
>>>
>>> Mind sharing your thoughts about the better value of the timeout? Probably 
>>> 25min?
>> From what you said that the average is 15-20, I think we can leave it set to 
>> 30.
>> But I wonder if we can do something to decrease the average time. ~20 min is 
>> a lot
>> even for FVP :) Have you tried setting send_slow to something lower than 
>> 100ms?
>> That said, we don't send too many chars to FVP, so I doubt it would play a 
>> major role
>> in the overall time.
> 
> I agree with the send_slow part. Actually I do have the same concern, here 
> are my current
> understanding and I think you will definitely help with your knowledge:
> If you check the full log of Dom0 booting, for example [1], you will find 
> that we wasted so
> much time in starting the services of the OS (modloop, udev-settle, etc). All 
> of these services
> are retried many times but in the end they are still not up, and from my 
> understanding they
> won’t affect the actual test(?) If we can somehow get rid of these services 
> from rootfs, I think
> we can save a lot of time.
> 
> And honestly, I noticed that qemu-alpine-arm64-gcc suffers from the same 
> problem and it also
> takes around 15min to finish. So if we managed to tailor the services from 
> the filesystem, we
> can save a lot of time.
That is not true. Qemu runs the tests relatively fast within few minutes. The 
reason you see e.g. 12 mins
for some Qemu jobs comes from the timeout we set in Qemu scripts. We don't have 
yet the solution (we could
do the same as Qubes script) to detect the test success early and exit before 
timeout. That is why currently
the only way for Qemu tests to finish is by reaching the timeout.

So the problem is not with the rootfs and services (the improvement would not 
be significant) but with
the simulation being slow. That said, this is something we all know and I 
expect FVP to only be used in scenarios
which cannot be tested using Qemu or real HW.

~Michal