[U-Boot] [RFC PATCH] test: py: Disable sleep test for qemu targets

[Stephen Warren]

On 12/04/2017 04:21 PM, Tom Rini wrote:
> On Mon, Dec 04, 2017 at 10:14:06AM -0700, Stephen Warren wrote:
>> On 12/04/2017 08:30 AM, Tom Rini wrote:
>>> On Mon, Dec 04, 2017 at 03:21:04PM +0100, Michal Simek wrote:
>>>> On 4.12.2017 15:03, Tom Rini wrote:
>>>>> On Mon, Dec 04, 2017 at 02:55:45PM +0100, Michal Simek wrote:
>>>>>> On 1.12.2017 23:44, Tom Rini wrote:
>>>>>>> On Fri, Dec 01, 2017 at 10:07:54AM -0700, Stephen Warren wrote:
>>>>>>>> On 12/01/2017 08:19 AM, Michal Simek wrote:
>>>>>>>>> Hi,
>>>>>>>>>
>>>>>>>>> On 1.12.2017 16:06, Heinrich Schuchardt wrote:
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> On 12/01/2017 03:46 PM, Michal Simek wrote:
>>>>>>>>>>> Qemu for arm32/arm64 has a problem with time setup.
>>>>>>>>>>
>>>>>>>>>> Wouldn't it be preferable to fix the root cause?
>>>>>>>>>
>>>>>>>>> Definitely that would be the best and IIRC I have tried to convince our
>>>>>>>>> qemu guy to do that but they have never done that.
>>>>>>>>
>>>>>>>> What is the exact failure condition? Is it simply that the test is still
>>>>>>>> slightly too strict about which delays it accepts, or is sleep outright
>>>>>>>> broken?
>>>>>>>>
>>>>>>>> You can use command-line option -k to avoid some tests. For example "-k not
>>>>>>>> sleep". That way, we don't have to hard-code the dependency into the test
>>>>>>>> source. Depending on the root cause (issue in U-Boot, or issue in just your
>>>>>>>> local version of qemu, or something that will never work) this might be
>>>>>>>> better?
>>>>>>>
>>>>>>> Even with the most recent relaxing of the sleep test requirements, I can
>>>>>>> still (depending on overall system load) have 'sleep' take too long, on
>>>>>>> QEMU.  I think it might have been half a second slow, but I don't have
>>>>>>> the log handy anymore.  Both locally and in travis we -k not sleep all
>>>>>>> of the qemu instances.
>>>>>>
>>>>>> ok. By locally do you mean just using -k not sleep?
>>>>>
>>>>> Yes, I have that in my CI scripts and similar.
>>>>
>>>> Wouldn't be easier to keep this in uboot-test-hooks repo with other
>>>> target setting?
>>>
>>> Or do as you did did and mark the tests as not allowed for qemu, yes.
>>>
>>>> What we are trying to do is that our testing group will run these tests
>>>> for me that's why it is just easier for me to change local
>>>> uboot-test-hooks repo instead of communicate with them what -k not XXX
>>>> parameters to add to certain scripts.
>>>>
>>>> It means in loop they will just run all tests on qemu, local targets and
>>>> in boardfarm. It is probably not big deal to tell them to add -k not
>>>> sleep for all qemu runs but I know that for some i2c testing qemu
>>>> doesn't emulate these devices that's why these tests fails. And the
>>>> amount of tests which we shouldn't run on qemu will probably grow.
>>>
>>> Well, I'm still open to possibly tweaking the allowed variance in the
>>> sleep test.  OTOH, if we just say "no QEMU" here, we can then go back to
>>> "sleep should be pretty darn accurate on HW" for the test too, and
>>> perhaps that's best.
>>
>> The fundamental problem of "over-sleeping" due to host system load/.. exists
>> with all boards. There's nothing specific to qemu here except that running
>> U-Boot on qemu on the host rather than on separate HW might more easily
>> trigger the "high load on the host" condition; I see the issue now and then
>> and manually retry that test, although that is a bit annoying.
>>
>> The original test was mostly intended to make sure that e U-Boot clock
>> didn't run at a significantly different rate to the host, since I had seen
>> that issue during development of some board support or as a regression
>> sometime. Perhaps the definition of "significantly different" should be more
>> like "1/2 rate or twice rate or more" rather than "off by a small fraction
>> of a second". That might avoid so many false positives.
> 
> I've pushed this up to 10 seconds and 0.5s worth of overrun and on
> qemu-mips here I see a 13.2s sleep.  That's pretty close to 1/3rd fast
> and to me a wrong-clocking value, yes?

For me the qemu-x86 build of mid-Nov commit of U-Boot running under the 
same qemu version that U-Boot's Travis CI builds use, "sleep 10" takes 
about 10.5 seconds (including my reaction time), so ~13.2 does sound 
like it's probably a bug. Or maybe qemu just isn't fast enough in its 
emulation to keep up with real-time? I'd hope not for something simple 
like this, assuming you're using a recent CPU, but maybe.