Use D3DSWAPEFFECT_FLIPEX on Windows 7.

Use D3DSWAPEFFECT_FLIPEX on Windows 7.

Reduces frame rate jitters on Windows 7 reported in crbug.com/82925
Committed: http://code.google.com/p/angleproject/source/detail?r=654

[nduca, 2011-05-24 04:10:42]

I suspect we still have frame rate consistency issues on WinXP and Vista.
However, this represents enough of an improvement in framerate stability that I
think its worth committing and getting into M13 while we sort out xp/vista
issues. This having been said, tell me if I'm wrong. :)

[kbr1, 2011-05-24 17:41:22]

+daniel, nicolas

[apatrick1, 2011-05-24 18:14:21]

Hmm I tried switching to FLIPEX and didn't notice any difference in performance.
Do you have some numbers? Also, it might be worth enabling FLIPEX support with a
macro in the chromium gyp files so other folks using ANGLE don't get a surprise.

[nduca, 2011-05-24 18:34:02]

Using FLIPEX is, afaik, the best-known method of rendering for windowed apps in
Win7. Can help me understand a use case for ANGLE where not using FLIPEX is
desirable?
http://msdn.microsoft.com/en-us/library/ee890072(v=vs.85).aspx

This gives a noticeable framerate stability improvement on my machine. Without
it, reported by a bunch of folks, present gets stuck in a beat pattern where
every other present blocks for 30ms while the other presents are free. This
leads to mayhem in terms of percieved smoothness.

I'm totally open to more discussion on why this is happening. But iirw, FLIPEX
is probably the right approach to use on win7 all the time.

On 2011/05/24 18:14:21, apatrick1 wrote:
> Hmm I tried switching to FLIPEX and didn't notice any difference in
performance.
> Do you have some numbers? Also, it might be worth enabling FLIPEX support with
a
> macro in the chromium gyp files so other folks using ANGLE don't get a
surprise.

[nduca, 2011-05-24 18:40:46]

Content like angry birds shows the stability improvement best.

With: solid 60 fps
Without: 30-1 fps pattern at the gpu process. Yes, averages to 60, but terrible
for animations.

[apatrick1, 2011-05-24 18:42:12]

On 2011/05/24 18:34:02, nduca wrote:
> Using FLIPEX is, afaik, the best-known method of rendering for windowed apps
in
> Win7. Can help me understand a use case for ANGLE where not using FLIPEX is
> desirable?
> http://msdn.microsoft.com/en-us/library/ee890072%28v=vs.85%29.aspx
> 
> This gives a noticeable framerate stability improvement on my machine. Without
> it, reported by a bunch of folks, present gets stuck in a beat pattern where
> every other present blocks for 30ms while the other presents are free. This
> leads to mayhem in terms of percieved smoothness.
> 
> I'm totally open to more discussion on why this is happening. But iirw, FLIPEX
> is probably the right approach to use on win7 all the time.
> 
> On 2011/05/24 18:14:21, apatrick1 wrote:
> > Hmm I tried switching to FLIPEX and didn't notice any difference in
> performance.
> > Do you have some numbers? Also, it might be worth enabling FLIPEX support
with
> a
> > macro in the chromium gyp files so other folks using ANGLE don't get a
> surprise.

No I was just interested because I couldn't tell any difference when I tried it.
Maybe its because we've cleared up other timing issues since then. LGTM for my
part.

[dgkoch, 2011-05-24 19:05:00]

There's a type in one of the comments, but otherwise LGTM.

http://codereview.appspot.com/4517096/diff/1/src/libEGL/Surface.cpp
File src/libEGL/Surface.cpp (right):

http://codereview.appspot.com/4517096/diff/1/src/libEGL/Surface.cpp#newcode151
src/libEGL/Surface.cpp:151: // We set BackBufferCount = 1 even when we use
D3DSWAPEFFEC_FLIPEX.
D3DSWAPEFFEC_FLIPEX -> D3DSWAPEFFECT_FLIPEX