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

[Lionel Landwerlin]

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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