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The Care and Feeding of the Android GPU
bonch writes "Charles Ying argues that Android's UX architecture has serious technical issues because, unlike the iPhone and Windows 7, Android composites the interface in software to retain compatibility with lower-class devices. Additionally, Android runs Java bytecode during animation, and garbage collection blocks the drawing system. Google engineers dismiss the desire for hardware-accelerated compositing and cite more powerful hardware and an avoidance of temporary objects as a solution to the collection pauses, but Ying argues that will just lead to [a lower] average battery life compared to devices like the iPhone."
I don't know enough about the Android graphics API, but if it's designed properly it should be possible for the client to always call the same function and the underlying implementation to select the code path most optimized for the platform. Mac OS X has one CoreGraphics API, and it either composites on the GPU or on the CPU depending on what's available. I don't see why Amdroiid can't do the same.
Don't blame me, I voted for Baltar.
You mean it's like a real, honest to goodness, computer operating system? Oh no! The horror! Guess you should stop making software for Windows, Linux, and OSX then, since the hardware can provided different capabilities for systems using the same operating system!
Somebody should really invent a programming interface for graphics. You could use hardware or software rendering for the same code, or generally a mixture of both, depending on the capabilities. It could be called "open graphics library" or something.
Escher was the first MC and Giger invented the HR department.
Debian seems to handle it just fine and (based on gcc) they're compiling for 14 different platforms* and 3 different kernels (linux, hurd, freebsd)
Is it that difficult to setup a similar thing in the app store? "Oh it looks like you're running an ARMv5 and a PowerVR GPU. We'll give you this binary."
Or, you do what Apple has always done with Fat Binaries. 68k to PPC. PPC to PPC64. PPC* to i386. i386 to x86_64. You could have one single fat binary that supported ppc, ppc64, i386 and x86_64. And it "Just worked". They were literally checkboxes in XCode. How many GPU and CPU solutions are there for the Android? This isn't low level Assembly code, it's compiled Java.
*alpha amd64 armel hppa hurd-i386 i386 ia64 kfreebsd-amd64 kfreebsd-i386 m68k mips mipsel powerpc s390 sh4 sparc sparc64
Let me tell you one thing about that: Java isn't the problem. In my definition of feeding the GPU: triangles/sec, fillrate and OpenGLES objects/sec, Java is just 10% behind a raw C benchmark like glbenchmark 1.1/2.0. They quoted 880kT/s, I managed 750kT/s in non native code. And to get that, you have to carefully feed the GPU with the right batch sizes, don't issue too many state changes, pack things interleaved in the video buffer, don't use dynamic point lights, etc etc. It isn't as bad as an NDS, but the Snapdragon GPU is quite hard to tame.
The problem with using the GPU is that every context switch requires a complete reinitialization of the GL context, even on a PC, alt tabbing into and from fullscreen games takes ages - it's fine when specific applications which requires the speed use it directly, but it's not when going from one activity to another gives you a loading screen.
Animation performance and touch responsiveness? Is that the best he can come up with for such a title? I have no idea what he's talking about, but scrolling the browser works just fine here on a not-so-recent HTC Desire. The only time things break down is when the garbage collector halts everything for a third of a second (see DDMS/logcat messages), and those pauses are reduced to sub 5ms in the new builds. That's tons more useful than rendering surfaces to quads and using OpenGL ES to draw them, and IMO, the Android team made the right decision.
That depends on the optimization and how that chipset actually handles throwing stuff on the screen. 'Optimize' may not just mean "format the data this certain way and it'll fly through the processors more quickly", it could also mean "use more polygons and lower-res textures because the chipset is better at moving verts around than filling texels". It doesn't matter that it's not low-level if it affects how the whole engine works.
"I like to lick butts!" by MobileTatsu-NJG (#32700246) (Score:5, Informative)
Add to that, you really don't need to optimise the code that you use for compositing on the GPU. A low-end mobile GPU can render something on the order of three million textured triangles per second. A typical mobile UI has a few dozen UI elements, with one texture and two triangles (one square) each. Even really crappy code is not going to come close to taxing the GPU. That's why we do compositing on the GPU - because it can run in its lowest-clocked mode and still provide fast performance, which lets you use the CPU for something else (or down-clock it too and save battery life).
I am TheRaven on Soylent News
massively different user experience on different devices
consider: different user experience on massively different devices
Why should it be otherwise? Should a quad-core i7 SLI provide exactly the same 'user experience' as an Atom netbook? Obviously not. It is not reasonable to expect the same results from increasingly diverse hardware. Android will be found on the lowest end freebee 'smart' phone China can make, while also appearing on the most outrageous hardware that doesn't present an immediate fire hazard. Where, exactly, was it written that the limits of one must apply to the other?
This problem has been solved over and over again. An architecture must exist that provides fall-back software implementations of hardware accelerated functions. When some app performs poorly due to inadequate hardware the user may find some other preoccupation or upgrade to a sufficient device.
What is the problem? At the moment it appears to be Google's obstinacy. This is a losing battle for them; they're creating a differentiating point among the manufacturers because the manufacturers can alter Android, including accelerating stuff with hardware. Marketing will then make claims about how xyz's Android is better than the other Androids because of xyz's special sauce (that may or may not port easily to some other collection of chips.) If the manufacturers don't the users will.
Lets hope Google wises up and deals with the issue properly.
Lurking at the bottom of the gravity well, getting old
Speaking as a former Googler, the smart people spin is somewhat overrated. Arrogant people is closer to the truth, and "smart" tends to mean "good at avoiding work".
Have you got your LWN subscription yet?
And you say that as an unbiased observer with no axe to grind, right? :-)
Right. I still own all my Google shares. However I am now properly disillusioned about a number of Google myths, but don't trust me. Ask any Googler, former or otherwise. In the latter case, make sure to do it out of earshot of other Googlers.
There are smart people at Google, and if they are really smart they learn early to keep their heads down. This seems to be the main sequence for large tech companies. Microsoft is far advanced on that path and Google seems more than a little determined to follow. The stack ranking system is nearly a carbon copy of Microsoft's, which in turn was copied from GE, and look how well that worked out. The result is inevitable degradation of the engineering culture. Now, warning about the negative consequences is not the same as axe grinding, quite the opposite.
Have you got your LWN subscription yet?
There's a myth going around that battery life is strongly affected by how efficient your code is. On most phone, it's simply not true. By far the biggest power drains are the screen and the radios (cellular, wifi, bluetooth). On Android, there's even a handy battery monitor built in that you can use to confirm this (Settings->About phone->Battery use). I can spend half an hour playing a high end, graphics intensive game (Hero of Sparta) on my Nexus One, and when I then check the battery use, I find that even while I was playing the screen and the cellular radio standby were still the dominant uses of power.
"I'm too busy to research this and form an educated opinion, but I do have time to tell everyone my uninformed opinion."