That said, I just sat down to test that, and eglSwapInterval doesn't
appear to be supported on Android, at least I don't see it in either
EGL10 or EGL11.


On Oct 2, 3:06 pm, Jeremy Statz <jst...@gmail.com> wrote:
> Back in the day glSwapInterval is what you'd use to synchronize with a
> CRT's refresh rate.  Setting it to one basically means that
> swapBuffers wouldn't happen until the next display refresh.  I'd
> thought it was dead and buried, but this appears to indicate
> otherwise:http://www.khronos.org/opengles/sdk/1.1/docs/man/eglSwapInterval.xml
>
> On a LCD screen presumably this means it'll clamp to 60Hz intervals
> when swapping the buffers, so you don't get a buffer being swapped
> halfway through a screen refresh.
>
> On Oct 2, 2:50 pm, Robert Green <rbgrn....@gmail.com> wrote:
>
>
>
>
>
>
>
> > I actually am adding a "safe mode" setting to the game that people can
> > use if it's freezing on their device.  I can't have it on all the time
> > or the game really is unplayably slow on the first gen phones and it
> > never seems to lock up on those - just snapdragons.
>
> > What are you guys talking about with the swap interval?  Is that a
> > framebuffer thing and if so, where do you handle it?
>
> > Thanks
>
> > On Oct 2, 12:25 pm, Jeremy Statz <jst...@gmail.com> wrote:
>
> > > I'm not mixing Native in with anything either, straight Java is enough
> > > trouble as is.  :P
>
> > > I noticed a definitely framerate hit with glFinish as well, but I'd
> > > rather suffer through that than have it forcibly lock up and reboot
> > > people's phones.  The worst thing is everybody but HTC seems just fine
> > > either way.  I really don't want to end up with a setting that says
> > > "Check this if you have an HTC handset".
>
> > > After updating a few things I'm less sold on glFinish actually fixing
> > > the problem.  In particular I'm starting to get e-mails from people
> > > who just bought a G2, and those seem to be a whole new raft of random
> > > stuff happening.  The most recent EVO update introduced flickering on
> > > the bottom half of the screen, which I thought glFinish fixed, but it
> > > doesn't sound like it was a 100% fix.  It might just come down to the
> > > framerate being slower in that case.
>
> > > That said, maybe it means SwapInterval is a sensible thing to try, so
> > > I'll give it a shot.
>
> > > On Oct 2, 12:04 pm, Leigh McRae <leigh.mc...@lonedwarfgames.com>
> > > wrote:
>
> > > >   Maybe set swap interval.  I have to say I feel your pain as Android is
> > > > starting to feel like PC when it comes to graphics drivers.
>
> > > > On 10/1/2010 9:03 PM, Robert Green wrote:
>
> > > > > Update - I just tested with eglWaitGL right before swapBuffers and I
> > > > > got the same nasty performance hit as glFinish.
>
> > > > > Any other ideas?
>
> > > > > On Oct 1, 7:43 pm, Robert Green<rbgrn....@gmail.com>  wrote:
> > > > >> I'm not mixing native with my context, but I get lots of reports of
> > > > >> freezing and have seen it on my Nexus One running both 2.1 and 2.2.
> > > > >> I'm just trying to find a solution to it.
>
> > > > >> On Oct 1, 7:04 pm, Leigh McRae<leigh.mc...@lonedwarfgames.com>  
> > > > >> wrote:
>
> > > > >>>    I would never call glFinish unless I was reading a buffer back.  
> > > > >>> I
> > > > >>> would also never call glFlush.  Swapping the buffers will do this.  
> > > > >>> When
> > > > >>> I was writing drivers it was common for glFlush to be a NOP.
> > > > >>> With that said, if you're mixing native with your context use the
> > > > >>> eglWait functions.  I know eglWaitGL says it's the same as glFinish 
> > > > >>> but
> > > > >>> I think the driver has a more clearer picture as to what is going 
> > > > >>> on.
> > > > >>> On 10/1/2010 7:43 PM, Robert Green wrote:
> > > > >>>> After more testing it's apparent that glFinish is causing nearly
> > > > >>>> double the frame time and it's not my code causing the issue.
> > > > >>>> Do you think adding glFlush() will do anything useful?  I did that 
> > > > >>>> on
> > > > >>>> my first 3D game and no one's ever complained about it freezing.
> > > > >>>> On Oct 1, 6:12 pm, Robert Green<rbgrn....@gmail.com>    wrote:
> > > > >>>>> Bad news... My testing shows a very significant performance hit 
> > > > >>>>> from
> > > > >>>>> doing this.
> > > > >>>>> Nexus One went from 40fps without ending on glFinish down to 
> > > > >>>>> 20-27.
> > > > >>>>> G1 went from 30fps down to about 5-10.
> > > > >>>>> This is not good.  I can't just put that in and call it fixed or 
> > > > >>>>> it'll
> > > > >>>>> make the game unplayable on low end phones.  I'll do some more 
> > > > >>>>> testing
> > > > >>>>> and see if it's my threading causing problems but I have a bad 
> > > > >>>>> feeling
> > > > >>>>> that it's not.
> > > > >>>>> On Sep 30, 3:30 pm, timedilation<udayan.k...@gmail.com>    wrote:
> > > > >>>>>> Jeremy, Glad to note that is has so far worked out for you.
> > > > >>>>>> Leigh, to your point, I also tested this with an explicit call to
> > > > >>>>>> eglWaitGL() function in my own version of GLSurfaceView 
> > > > >>>>>> (basically
> > > > >>>>>> this call was added just before the eglSwapBuffer() call). This 
> > > > >>>>>> also
> > > > >>>>>> fixed thefreezingin my case. I just resorted to using glFinish()
> > > > >>>>>> because that way I didn't have to use my own version of 
> > > > >>>>>> GLSurfaceView.
> > > > >>>>>> So if Google changed their GLSurfaceView in the next release, my 
> > > > >>>>>> code
> > > > >>>>>> will not be affected much.
> > > > >>>>>> When I mentioned this to a Google developer advocate and he said 
> > > > >>>>>> that
> > > > >>>>>> this still needs to be fixed in the OS since it is an OS level 
> > > > >>>>>> bug.
> > > > >>>>>> eglSwapBuffers() called glFlush() internally anyways but it ends 
> > > > >>>>>> up
> > > > >>>>>> getting deadlocked once in a while on some of these devices we 
> > > > >>>>>> have
> > > > >>>>>> seen. Explicitly calling eglWaitGL() or glFinish() in the 
> > > > >>>>>> renderloop
> > > > >>>>>> *before* the eglSwapBuffers() appears to have fixed this issue 
> > > > >>>>>> in many
> > > > >>>>>> (if not all) cases. I still have users reporting to me that their
> > > > >>>>>> phonesfreezingeven with the latest update, albeit much less
> > > > >>>>>> frequently.
> > > > >>>>>> Let's hope for Google to fix this once and for all in their next
> > > > >>>>>> release.
> > > > >>>>>> On Sep 30, 2:26 pm, Leigh McRae<leigh.mc...@lonedwarfgames.com>
> > > > >>>>>> wrote:
> > > > >>>>>>>     You might want to look into the eglWait functions that are 
> > > > >>>>>>> used to
> > > > >>>>>>> synchronize with the native rendering system.
> > > > >>>>>>> On 9/30/2010 2:07 PM, Jeremy Statz wrote:
> > > > >>>>>>>> I've tested this extensively at this point (including a 
> > > > >>>>>>>> 20-hour run on
> > > > >>>>>>>> an Incredible) and I think you're right, calling glFinish() 
> > > > >>>>>>>> seems like
> > > > >>>>>>>> it largely fixes the problem.  Wow, I'd really thought that 
> > > > >>>>>>>> one was
> > > > >>>>>>>> outmoded.
> > > > >>>>>>>> Related to this, the most recent EVO update was causing the
> > > > >>>>>>>> framebuffer to flicker with black squares sometimes on my 
> > > > >>>>>>>> wallpapers,
> > > > >>>>>>>> and calling glFinish() fixed that too.  And it fixed a similar
> > > > >>>>>>>> corruption I had reported a few days ago on the Nexus one.  
> > > > >>>>>>>> It's the
> > > > >>>>>>>> magic HTC fixer-upper!
> > > > >>>>>>>> TimeDilation, you're my hero.
> > > > >>>>>>>> On Sep 21, 3:26 pm, timedilation<udayan.k...@gmail.com>      
> > > > >>>>>>>> wrote:
> > > > >>>>>>>>> It was happening between 1 - 45 minutes into the app. Every 
> > > > >>>>>>>>> single
> > > > >>>>>>>>> time.
> > > > >>>>>>>>> Maybe this is not a permanent fix and maybe it has just 
> > > > >>>>>>>>> reduced the
> > > > >>>>>>>>> frequency of freezings. But as I mentioned before, so far I 
> > > > >>>>>>>>> have not
> > > > >>>>>>>>> seen a single freeze since I made that change 2 days ago.
> > > > >>>>>>>>> On Sep 21, 4:05 pm, Robert Green<rbgrn....@gmail.com>      
> > > > >>>>>>>>> wrote:
> > > > >>>>>>>>>> And it was happening reliably before?
> > > > >>>>>>>>>> On Sep 21, 12:48 pm, timedilation<udayan.k...@gmail.com>     
> > > > >>>>>>>>>>  wrote:
> > > > >>>>>>>>>>> I haven't seen any freeze since making that change (I am 
> > > > >>>>>>>>>>> only testing
> > > > >>>>>>>>>>> this on the HTC Desire running 2.2)
> > > > >>>>>>>>>>> On Sep 21, 1:32 pm, Robert Green<rbgrn....@gmail.com>      
> > > > >>>>>>>>>>> wrote:
> > > > >>>>>>>>>>>> So after finishing with glFinish(), you haven't seen a 
> > > > >>>>>>>>>>>> freeze at all
> > > > >>>>>>>>>>>> or you just saw one now?  I'm not sure what to make of the 
> > > > >>>>>>>>>>>> "until now"
> > > > >>>>>>>>>>>> part :)
> > > > >>>>>>>>>>>> If you really think that's making a difference, I'll try 
> > > > >>>>>>>>>>>> it out and
> > > > >>>>>>>>>>>> see if it makes a difference for my games as well, though 
> > > > >>>>>>>>>>>> I have to
> > > > >>>>>>>>>>>> play for about an hour to see it happen.
> > > > >>>>>>>>>>>> On Sep 21, 12:10 pm, timedilation<udayan.k...@gmail.com>   
> > > > >>>>>>>>>>>>    wrote:
> > > > >>>>>>>>>>>>> Not sure if the following will fix thefreezingin all 
> > > > >>>>>>>>>>>>> cases but it
> > > > >>>>>>>>>>>>> appears to have fixed it in my app. I still have my 
> > > > >>>>>>>>>>>>> fingers crossed
> > > > >>>>>>>>>>>>> about it although my app hasn't frozen for a while now - 
> > > > >>>>>>>>>>>>> even when I
> > > > >>>>>>>>>>>>> let it run overnight on an HTC Desire 2.2.
> > > > >>>>>>>>>>>>> I first took the source code of GLSurfaceView into my 
> > > > >>>>>>>>>>>>> custom class and
> > > > >>>>>>>>>>>>> added this line immediately before the eglSwapBuffer() 
> > > > >>>>>>>>>>>>> call in the
> > > > >>>>>>>>>>>>> EGLHelper class function:
> > > > >>>>>>>>>>>>> mEgl.glWaitGL();
> > > > >>>>>>>>>>>>> This is a blocking call that waits for all existing GL 
> > > > >>>>>>>>>>>>> commands to be
> > > > >>>>>>>>>>>>> processed before returning. With this line, 
> > > > >>>>>>>>>>>>> thefreezingseems to have
> > > > >>>>>>>>>>>>> stopped.
> > > > >>>>>>>>>>>>> I then realized that the glFinish() function does the 
> > > > >>>>>>>>>>>>> same thing. So I
> > > > >>>>>>>>>>>>> went back to using the built-in GLSurfaceView and added 
> > > > >>>>>>>>>>>>> the glFinish()
> > > > >>>>>>>>>>>>> call at the very end of my renderer.onDrawFrame() 
> > > > >>>>>>>>>>>>> function. This had
> > > > >>>>>>>>>>>>> the same effect and I haven't seen a freeze until now. I 
> > > > >>>>>>>>>>>>> suspect this
> > > > >>>>>>>>>>>>> call is just making the loop wait explicitly for all GL 
> > > > >>>>>>>>>>>>> commands to be
> > > > >>>>>>>>>>>>> processed before rendering again. I took a look in the 
> > > > >>>>>>>>>>>>> profiler and
> > > > >>>>>>>>>>>>> this call did not add any extra overhead (likely because 
> > > > >>>>>>>>>>>>> the
> > > > >>>>>>>>>>>>> eglSwapBuffers() is also a blocking call and does the 
> > > > >>>>>>>>>>>>> same thing -
> > > > >>>>>>>>>>>>> except that it freezes randomly).
> > > > >>>>>>>>>>>>> If thefreezingstarts again, I will update this post.
> > > > >>>>>>>>>>>>> Hope
>
> ...
>
> read more »

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