Re: Reconfigurable OA queries

[Lionel Landwerlin <lionel.g.landwerlin@intel.com>]

On 09/10/2019 09:40, Lionel Landwerlin wrote:
> On 09/10/2019 02:26, Chris Wilson wrote:
>> Quoting Lionel Landwerlin (2019-10-09 00:14:41)
>>> On 09/10/2019 00:40, Chris Wilson wrote:
>>>> This is Lionel's work to enable OA for Vulkan, greatly bastardised on
>>>> top of the struct_mutex removal. It claims to be doing the right
>>>> thing...
>>>> -Chris
>>>>
>>>>
>>> Thanks a lot of picking this up.
>>>
>>> I'm aware of an issue with patch 9 as I can see requests with perf
>>> queries being preempted. Looking into that, but not quite there yet.
>> Outside of the masking issue where a later request on the same context
>> will mask the nopreempt request, if that nopreempt flag is set on the
>> last submitted request to ELSP[0], we will not allow that context to be
>> preempted before we consider the request to be completed.
>
>
> Oh... interesting!


You're right as usual.


There are a few places where I could see that happen.

We implement vkQueueWaitIdle by submitting an empty batch and waiting on 
the signaling of the fence.


I can workaround this in Anv by flagging all execbuf with a perf config 
for as long as i915-perf is opened.

I could also flag the request with nopreempt even with reconfiguration 
wasn't requested, but the perf stream is flagged with hold preemption 
for the given context, which is probably the right thing to do.


Thanks a lot for pointing this out!


-Lionel


>
>
>>
>>> I think there is a dependency issue with patch 8. We also use
>>> cliprects_ptr for fences.
>> Hmm, I was expecting the flag validation to be in the first patch to add
>> extension parsing, but we are missing the test if both flags are set,
>> reject the execbuf.
>>
>>> If we start reusing it for extended parameters, we need to make fences
>>> the first extended param.
>> Why?
>> -Chris
>>
> How do we pass a reconfigure of OA together with an array of fences?
>
>
> -Lionel
>
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