Re: [igt-dev] [i-g-t] tests/i915/exec_balancer: Added Skip Guc Submission

[Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>]

Old commit message:

"""
This a known failure when running 
igt@gem_exec_balancer@bonded-(dual|pair|sync)
tests with GuC submission.The hang is expected with GuC submission since the
test was written to expect execlist scheduling hence added skip if Guc
submission enabled.
"""

New commit message:

On 09/12/2021 08:20, Mastan Katragadda wrote:
> This test makes assumptions about the backend scheduling algorithm that
> a real world UMD would never assume. This test is not testing a UMD-KMD
> contract, rather a specific backend.It is an invalid test case thus we
> are skipping.
> 
> Changes Since v1:
>               -Updated commit message

Well that hasn't been really improved at all an is still totally opaque. 
No mention whether it is all or some subtests, no mention of what 
assumptions, what exact usage of the ABI is discouraged, not much more 
than pure rewording.

No desire to split into passing and non passing tests and only skip 
latter group?

Or to add a twist, what about making the specific subtests which hang 
with GuC, expect to hang and therefore pass?

That would a) document the failing corner case of the ABI and more 
importantly b) keep exercising the i915 code paths which sit between the 
uAPI and the GuC firmware?

If that is not acceptable, and I do acknowledge to the cost to CI time, 
then architects should ack and in my mind the ack should mean one of the 
two things. Either:

  1) We know there is coverage for the same i915 code paths elsewhere in 
IGT. Or:

  2) We are willingly dropping coverage for these i915 code paths on GuC 
platforms with the risk that the code might unknowingly bit rot and 
cause more serious security issues down the line.

Regards,

Tvrtko

> 
> Cc: Matthew Brost <matthew.brost@intel.com>
> Signed-off-by: Mastan Katragadda <mastanx.katragadda@intel.com>
> ---
>   tests/i915/gem_exec_balancer.c | 1 +
>   1 file changed, 1 insertion(+)
> 
> diff --git a/tests/i915/gem_exec_balancer.c b/tests/i915/gem_exec_balancer.c
> index cc07a5a9..d58734ab 100644
> --- a/tests/i915/gem_exec_balancer.c
> +++ b/tests/i915/gem_exec_balancer.c
> @@ -3320,6 +3320,7 @@ igt_main
>   
>   	igt_subtest_group {
>   		igt_fixture {
> +			igt_require(!gem_using_guc_submission(i915));
>   			intel_allocator_multiprocess_start();
>   		}
>   
>