Re: [igt-dev] [PATCH i-g-t 2/3] i915/gem_ctx_shared: Make gem_ctx_shared understand static priority mapping

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

On 05/10/2021 00:26, Daniele Ceraolo Spurio wrote:
> 
> 
> On 9/16/2021 11:03 AM, Matthew Brost wrote:
>> The i915 currently has 2k visible priority levels which are currently
>> unique. This is changing to statically map these 2k levels into 3
>> buckets:
>>
>> low: < 0
>> mid: 0
>> high: > 0
>>
>> Update gem_ctx_shared to understand this. This entails updating
>> promotion test to use 3 levels that will map into different buckets and
>> also add bit of delay after releasing a cork beforing completing the
>> spinners to give time to the i915 schedule to process the fence and
>> release and queue the requests.
>>
>> v2: Add a delay between starting releasing spinner and cork in
>> promotion
>> v3:
>>   (Daniele)
>>    - Always add delay, update commit message
>>
>> Signed-off-by: Matthew Brost <matthew.brost@intel.com>
>> ---
>>   tests/i915/gem_ctx_shared.c | 5 +++--
>>   1 file changed, 3 insertions(+), 2 deletions(-)
>>
>> diff --git a/tests/i915/gem_ctx_shared.c b/tests/i915/gem_ctx_shared.c
>> index ea1b5dd1b..7f88871b8 100644
>> --- a/tests/i915/gem_ctx_shared.c
>> +++ b/tests/i915/gem_ctx_shared.c
>> @@ -622,6 +622,7 @@ static void unplug_show_queue(int i915, struct 
>> igt_cork *c, uint64_t ahnd,
>>       igt_cork_unplug(c); /* batches will now be queued on the engine */
>>       igt_debugfs_dump(i915, "i915_engine_info");
>> +    usleep(250000);
> 
> Same as previous patch, with a comment added:
> 
> Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>

Come on guys, it is a bit bad and lazy for good taste no? 250ms more 
test runtime, multiplied by number of tests and subtests (engines) will 
add up and over shadows the current test time. For instance current 
state is:

# tests/gem_ctx_shared --r *promotion*
IGT-Version: 1.26-NO-GIT (x86_64) (Linux: 5.15.0-rc4 x86_64)
Starting subtest: Q-promotion
Starting dynamic subtest: rcs0
Dynamic subtest rcs0: SUCCESS (0.174s)
Starting dynamic subtest: bcs0
Dynamic subtest bcs0: SUCCESS (0.224s)
Starting dynamic subtest: vcs0
Dynamic subtest vcs0: SUCCESS (0.153s)
Starting dynamic subtest: vecs0
Dynamic subtest vecs0: SUCCESS (0.153s)
Subtest Q-promotion: SUCCESS (0.708s)

This patch instantly makes this 1.7 seconds instead. Add the in/out 
order subtests, other tests, platforms with more engines, in a world 
where CI time budget is scarce - can't we do better than this and not 
settle on sprinkling of usleep all over the place?

Like maybe add out fences to the two requests, merge them, and wait on 
that (since there is no implicit write declared so set domain does not 
suffice)?

Unless I am missing something it would be strictly correct for execlists 
backend as well since it now works just because it is fast enough.

Regards,

Tvrtko

> 
> Daniele
> 
>>       for (int n = 0; n < ARRAY_SIZE(spin); n++) {
>>           ahnd = spin[n]->ahnd;
>> @@ -831,10 +832,10 @@ static void promotion(int i915, const 
>> intel_ctx_cfg_t *cfg, unsigned ring)
>>       gem_context_set_priority(i915, ctx[LO]->id, MIN_PRIO);
>>       ctx[HI] = intel_ctx_create(i915, &q_cfg);
>> -    gem_context_set_priority(i915, ctx[HI]->id, 0);
>> +    gem_context_set_priority(i915, ctx[HI]->id, MAX_PRIO);
>>       ctx[NOISE] = intel_ctx_create(i915, &q_cfg);
>> -    gem_context_set_priority(i915, ctx[NOISE]->id, MIN_PRIO/2);
>> +    gem_context_set_priority(i915, ctx[NOISE]->id, 0);
>>       result = gem_create(i915, 4096);
>>       result_offset = get_offset(ahnd, result, 4096, 0);
>