[igt-dev] [PATCH i-g-t 3/3] igt/gem_sync: Exercising waiting while keeping the GPU busy

[Antonio Argenziano]

On 10/08/18 10:51, Chris Wilson wrote:
> Quoting Antonio Argenziano (2018-08-10 18:41:22)
>>
>>
>> On 10/08/18 04:01, Chris Wilson wrote:
>>> Normally we wait on the last request, but that overlooks any
>>> difficulties in waiting on a request while the next is being qeued.
>>
>> /s/qeued/queued
>>
>>> Check those.
>>>
>>> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
>>> ---
>>>    tests/gem_sync.c | 72 ++++++++++++++++++++++++++++++++++++++++++++++++
>>>    1 file changed, 72 insertions(+)
>>>
>>> diff --git a/tests/gem_sync.c b/tests/gem_sync.c
>>> index c697220ad..fb209977d 100644
>>> --- a/tests/gem_sync.c
>>> +++ b/tests/gem_sync.c
>>> @@ -294,6 +294,74 @@ wakeup_ring(int fd, unsigned ring, int timeout, int wlen)
>>>        igt_assert_eq(intel_detect_and_clear_missed_interrupts(fd), 0);
>>>    }
>>>    
>>
>>> +     intel_detect_and_clear_missed_interrupts(fd);
>>> +     igt_fork(child, num_engines) {
>>> +             double start, end, elapsed;
>>> +             unsigned long cycles;
>>> +             igt_spin_t *spin[2];
>>> +             uint32_t cmd;
>>> +
>>> +             spin[0] = __igt_spin_batch_new(fd,
>>> +                                            .engine = ring,
>>> +                                            .flags = IGT_SPIN_FAST);
>>> +             cmd = *spin[0]->batch;
>>> +
>>> +             spin[1] = __igt_spin_batch_new(fd,
>>> +                                            .engine = ring,
>>> +                                            .flags = IGT_SPIN_FAST);
>>> +             igt_assert(*spin[1]->batch == cmd);
>>> +
>>> +             start = gettime();
>>> +             end = start + timeout;
>>> +             cycles = 0;
>>> +             do {
>>> +                     for (int loop = 0; loop < 1024; loop++) {
>>> +                             igt_spin_t *s = spin[loop & 1];
>>> +
>>> +                             igt_spin_batch_end(s);
>>> +                             gem_sync(fd, s->handle);
>>
>> How does the test fail if the sync goes wrong? Hang detector on the
>> queued batch?
> 
> We have a hang detector for both missed wakeups and GPU hangs. As tests
> goes it's fairly tame, but in essence this entire file is about trying
> to trick the HW+driver into not sending an interrupt back to userspace.
> Just a very narrow stress test, over and over again from slightly
> different angles.

I see.

Reviewed-by: Antonio Argenziano <antonio.argenziano at intel.com>

> -Chris
>