[PATCH] DRI2: By default, throttle after two pending swaps.

Jamey Sharp jamey at minilop.net
Tue May 13 00:18:49 PDT 2014

On Tue, May 13, 2014 at 12:01 AM, Chris Wilson <chris at chris-wilson.co.uk> wrote:
> On Mon, May 12, 2014 at 06:30:47PM -0700, Jamey Sharp wrote:
>> According to Chris Wilson, the Intel driver has a horrifying kludge to
>> get triple-buffering despite the swap_limit being set to only allow
>> double-buffering by default. This kludge makes OML_sync_control unusable
>> if the Intel driver goes into page-flipping mode.
>> Since triple-buffering is preferred for most applications, let's make it
>> the default in the server and allow the drivers to quit lying to the X
>> server about when swaps complete.
> No, it is not that simple. GetBuffers() can only be allowed to proceed
> after the driver has arranged for the call to return the right buffers
> to the client. In the event that a client scheduled a future swap, most
> drivers will defer the buffer exchange until the swap is actually
> performed - limiting the client to double buffering to avoid
> complications in reporting the wrong buffers.

Alright. How do you believe the Intel driver's buggy and unusable
implementation of OML_sync_control should be fixed?

I'd also be delighted to see patches to make SNA pass the new Piglit
tests. I tried to fix that before I turned to UXA but I got lost in
too many different DRI2SwapComplete calls with spec-violating
parameters before I even got to checking whether it was reliably
syncing to vertical retrace. I'd be happy to send along the one patch
I could figure out if you want it though.


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