[Mesa-dev] [PATCH 4/6] gallium: add way for drivers to create fences without flushing

[Rob Clark]

On Tue, Apr 5, 2016 at 9:04 AM, Marek Olšák <maraeo at gmail.com> wrote:
> On Mon, Apr 4, 2016 at 2:43 PM, Rob Clark <robdclark at gmail.com> wrote:
>> Hmm, what are the requirements of eglClientWaitSyncKHR() about having
>> current context bound?  Not being thread-safe (ie. being associated w/
>> current ctx) is pretty important to allow apps that create fences at
>> in-opportune times to not force a mid-frame flush for tilers.. :-(
>
> There are 2 kinds of fences already:
> - owned by pipe_screen: pipe_fence_handle
> - owned by pipe_context: PIPE_QUERY_GPU_FINISHED
>
> I think the latter is what you want.

yes, but very much no... query is a pretty horrible interface for this
(for same/similar reason that timestamp queries are horrible for
tilers) since it assumes fences are actually a single point in gpu
rendering pipeline ;-)

When I get some time for v2 of this patchset, I think adding an
optional (might be null) pipe_context pointer to
screen->fence_finish() seems like the most reasonable option.

BR,
-R

> Marek