[Mesa-dev] [PATCH 2/3] radv: remove unnecessary FLUSH_AND_INV_CB when initializing DCC

[Samuel Pitoiset]

After having a deeper look at the cache flushes when initializing DCC, 
it seems like we are dumb.

In case the compute path is used for clearing DCC, we set the following 
flags:

- CS_PARTIAL_FLUSH

- INV_VMEM_L1

- WRITEBACK_GLOBAL_L2

- FLUSH_AND_INV_CB

- FLUSH_ANV_INV_CB_META

On GFX9, the driver will emit:

- one RELEASE_MEM with TC_ACTION_ENA | TC_MD_ACTION_ENA

- one ACQUIRE_MEM with TC_WB_ACTION_ENA | TC_NC_ACTION_ENA

- one ACQUIRE_MEM with TCL1_ACTION_ENA

This seems overkill to me... Emitting one RELEASE_MEM with TC_ACTION_ENA 
| TC_WB_ACTION_ENA (ie. INV_GLOBAL_L2) should be enough?

On 3/19/19 2:03 PM, Samuel Pitoiset wrote:
>
> On 3/19/19 1:56 PM, Bas Nieuwenhuizen wrote:
>> That it does not use it is exactly why we need to make sure the CB
>> data is not in the CB cache by flushing it?
> Why only for DCC?
>>
>> On Tue, Mar 19, 2019 at 12:15 PM Samuel Pitoiset
>> <samuel.pitoiset at gmail.com> wrote:
>>> The clear operation (ie. compute) doesn't use the CB caches.
>>>
>>> Signed-off-by: Samuel Pitoiset <samuel.pitoiset at gmail.com>
>>> ---
>>>   src/amd/vulkan/radv_cmd_buffer.c | 3 +--
>>>   1 file changed, 1 insertion(+), 2 deletions(-)
>>>
>>> diff --git a/src/amd/vulkan/radv_cmd_buffer.c 
>>> b/src/amd/vulkan/radv_cmd_buffer.c
>>> index 5bb3b51684e..b6035dfbbc5 100644
>>> --- a/src/amd/vulkan/radv_cmd_buffer.c
>>> +++ b/src/amd/vulkan/radv_cmd_buffer.c
>>> @@ -4583,8 +4583,7 @@ static void 
>>> radv_init_color_image_metadata(struct radv_cmd_buffer *cmd_buffer,
>>>
>>>                  state->flush_bits |= radv_clear_dcc(cmd_buffer, 
>>> image, value);
>>>
>>> -               state->flush_bits |= RADV_CMD_FLAG_FLUSH_AND_INV_CB |
>>> - RADV_CMD_FLAG_FLUSH_AND_INV_CB_META;
>>> +               state->flush_bits |= 
>>> RADV_CMD_FLAG_FLUSH_AND_INV_CB_META;
>>>
>>>                  radv_update_fce_metadata(cmd_buffer, image,
>>> need_decompress_pass);
>>> -- 
>>> 2.21.0
>>>
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