[Mesa-dev] [PATCH] anv/query: ensure visibility of reset before copying query results

[Lionel Landwerlin]

I've uploaded this MR : 
https://gitlab.freedesktop.org/mesa/mesa/merge_requests/776

Which actually highlights a bigger issue with our queries.

-Lionel

On 01/05/2019 11:58, Lionel Landwerlin wrote:
> Experimenting a bit with the visibility of PIPE_CONTROL writes & MI_* 
> commands I realized those are not coherent.
> Essentially anything written with a PIPE_CONTROL will be visible to 
> MI_* commands only after some time.
> In my experiment I had to insert 2 MI instructions after the 
> PIPE_CONTROL write to actually have the following MI_COPY_MEM_MEM 
> command pick up what was written by the pipe control.
>
> So my recommendation would be to always write the availability with 
> the same part of the command streamer (PIPE_CONTROL).
> So that the sequences of writes to the same location are not subject 
> to complicated synchronization rules.
>
> Essentially just make emit_query_availability() take an additional 
> boolean and then use it in CmdResetQueryPool().
>
> -Lionel
>
> On 30/04/2019 18:18, Lionel Landwerlin wrote:
>> Let me check the new tests and see if where the problem is.
>> Thanks for letting us know!
>>
>> -Lionel
>>
>> On 30/04/2019 13:43, Iago Toral Quiroga wrote:
>>> Specifically, vkCmdCopyQueryPoolResults is required to see the effect
>>> of a previous vkCmdResetQueryPool. This may not work currently when
>>> query execution is still on going, as some of the queries may become
>>> available asynchronously after the reset.
>>>
>>> Fixes new CTS tests:
>>> dEQP-VK.query_pool.statistics_query.reset_before_copy.*
>>> ---
>>>
>>> Jason, do you have any better ideas?
>>>
>>>   src/intel/vulkan/genX_query.c | 13 +++++++++++++
>>>   1 file changed, 13 insertions(+)
>>>
>>> diff --git a/src/intel/vulkan/genX_query.c 
>>> b/src/intel/vulkan/genX_query.c
>>> index 146435c3f8f..08b013f6351 100644
>>> --- a/src/intel/vulkan/genX_query.c
>>> +++ b/src/intel/vulkan/genX_query.c
>>> @@ -383,6 +383,19 @@ void genX(CmdResetQueryPool)(
>>>      ANV_FROM_HANDLE(anv_cmd_buffer, cmd_buffer, commandBuffer);
>>>      ANV_FROM_HANDLE(anv_query_pool, pool, queryPool);
>>>   +   /* From the Vulkan spec:
>>> +    *
>>> +    *    "vkCmdCopyQueryPoolResults is guaranteed to see the effect of
>>> +    *     previous uses of vkCmdResetQueryPool in the same queue, 
>>> without
>>> +    *     any additional synchronization. Thus, the results will 
>>> always
>>> +    *     reflect the most recent use of the query."
>>> +    *
>>> +    * So we need to make sure that any on-going queries are 
>>> finished by
>>> +    * the time we emit the reset.
>>> +    */
>>> +   cmd_buffer->state.pending_pipe_bits |= ANV_PIPE_CS_STALL_BIT;
>>> +   genX(cmd_buffer_apply_pipe_flushes)(cmd_buffer);
>>> +
>>>      for (uint32_t i = 0; i < queryCount; i++) {
>>>         anv_batch_emit(&cmd_buffer->batch, GENX(MI_STORE_DATA_IMM), 
>>> sdm) {
>>>            sdm.Address = anv_query_address(pool, firstQuery + i);
>>
>>
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