Ieri è stato postato un commento che chiarisce bene il concetto di accelerazione hw, vi consiglio di leggerlo:
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How about some Android graphics true facts?
I get tired of seeing so much misinformation posted and repeated all over the place about how graphics rendering works on Android. Here is some truth:
• Android has always used some hardware accelerated drawing. Since before 1.0 all window compositing to the display has been done with hardware.
• This means that many of the animations you see have always been hardware accelerated: menus being shown, sliding the notification shade, transitions between activities, pop-ups and dialogs showing and hiding, etc.
• Android did historically use software to render the contents of each window. For example in a UI like http://www.simplemobilereview.com/wp...-home-menu.png there are four windows: the status bar, the wallpaper, the launcher on top of the wallpaper, and the menu. If one of the windows updates its contents, such as highlighting a menu item, then (prior to 3.0) software is used to draw the new contents of that window; however none of the other windows are redrawn at all, and the re-composition of the windows is done in hardware. Likewise, any movement of the windows such as the menu going up and down is all hardware rendering.
• Looking at drawing inside of a window, you don’t necessarily need to do this in hardware to achieve full 60fps rendering. This depends very much on the number of pixels in your display and the speed of your CPU. For example, Nexus S has no trouble doing 60fps rendering of all the normal stuff you see in the Android UI like scrolling lists on its 800x480 screen. The original Droid however struggled with a similar screen resolution.
• "Full" hardware accelerated drawing within a window was added in Android 3.0. The implementation in Android 4.0 is not any more full than in 3.0. Starting with 3.0, if you set the flag in your app saying that hardware accelerated drawing is allowed, then all drawing to the application’s windows will be done with the GPU. The main change in this regard in Android 4.0 is that now apps that are explicitly targeting 4.0 or higher will have acceleration enabled by default rather than having to put android:handwareAccelerated="true" in their manifest. (And the reason this isn’t just turned on for all existing applications is that some types of drawing operations can’t be supported well in hardware and it also impacts the behavior when an application asks to have a part of its UI updated. Forcing hardware accelerated drawing upon existing apps will break a significant number of them, from subtly to significantly.)
• Hardware accelerated drawing is not all full of win. For example on the PVR drivers of devices like the Nexus S and Galaxy Nexus, simply starting to use OpenGL in a process eats about 8MB of RAM. Given that our process overhead is about 2MB, this is pretty huge. That RAM takes away from other things, such as the number of background processes that can be kept running, potentially slowing down things like app switching.
• Because of the overhead of OpenGL, one may very well not want to use it for drawing. For example some of the work we are doing to make Android 4.0 run well on the Nexus S has involved turning off hardware accelerated drawing in parts of the UI so we don’t lose 8MB of RAM in the system process, another 8MB in the phone process, another 8MB in the system UI process, etc. Trust me, you won’t notice -- there is just no benefit on that device in using OpenGL to draw something like the status bar, even with fancy animations going on in there.
• Hardware accelerated drawing is not a magical silver bullet to butter-smooth UI. There are many different efforts that have been going on towards this, such as improved scheduling of foreground vs. background threads in 1.6, rewriting the input system in 2.3, strict mode, concurrent garbage collection, loaders, etc. If you want to achieve 60fps, you have 20 milliseconds to handle each frame. This is not a lot of time. Just touching the flash storage system in the thread that is running the UI can in some cases introduce a delay that puts you out of that timing window, especially if you are writing to storage.
• A recent example of the kinds of interesting things that impact UI smoothness: we noticed that ICS on Nexus S was actually less smooth when scrolling through lists than it was on Gingerbread. It turned out that the reason for this was due to subtle changes in timing, so that sometimes in ICS as the app was retrieving touch events and drawing the screen, it would go to get the next event slightly before it was ready, causing it to visibly miss a frame while tracking the finger even though it was drawing the screen at a solid 60fps.
• When people have historically compared web browser scrolling between Android and iOS, most of the differences they are seeing are not due to hardware accelerated drawing. Originally Android went a different route for its web page rendering and made different compromises: the web page is turned in to a display list, which is continually rendered to the screen, instead of using tiles. This has the benefit that scrolling and zooming never have artifacts of tiles that haven’t yet been drawn. Its downside is that as the graphics on the web page get more complicated to draw the frame rate goes down. As of Android 3.0, the browser now uses tiles, so it can maintain a consistent frame rate as you scroll or zoom, with the negative of having artifacts when newly needed tiles can’t be rendered quickly enough. The tiles themselves are rendered in software, which I believe is the case for iOS as well. (And this tile-based approach could be used prior to 3.0 without hardware accelerated drawing; as mentioned previously, the Nexus S CPU can easily draw the tiles to the window at 60fps.)
• Hardware accleration does not magically make drawing performance problems disappear. There is still a limit to how much the GPU can do. A recent interesting example of this is tablets built with Tegra 2 -- that GPU can touch every pixel of a 1280x800 screen about 2.5 times at 60fps. Now consider the Android 3.0 tablet home screen where you are switching to the all apps list: you need to draw the background (1x all pixels), then the layer of shortcuts and widgets (let’s be nice and say this is .5x all pixels), then the black background of all apps (1x all pixels), and the icons and labels of all apps (.5x all pixels). We’ve already blown our per-pixel budget, and we haven’t even composited the separate windows to the final display yet. To get 60fps animation, Android 3.0 and later use a number of tricks. A big one is that it tries to put all windows into overlays instead of having to copy them to the framebuffer with the GPU. In the case here even with that we are still over-budget, but we have another trick: because the wallpaper on Android is in a separate window, we can make this window larger than the screen to hold the entire bitmap. Now, as you scroll, the movement of the background doesn’t require any drawing, just moving its window... and because this window is in an overlay, it doesn’t even need to be composited to the screen with the GPU.
• As device screen resolution goes up, achieving a 60fps UI is closely related to GPU speed and especially the GPU’s memory bus bandwidth. In fact, if you want to get an idea of the performance of a piece of hardware, always pay close attention to the memory bus bandwidth. There are plenty of times where the CPU (especially with those wonderful NEON instructions) can go a lot faster than the memory bus.
E' stato aperto un nuovo thread su xda inerente alla rom con l'hack per l'accelerazione hw, così da non intasare il thread dev:
Inoltre, un altro video sulla rom con l'hack per l'accelerazione hw:Quote:
This is a thread for all of those interested in the HW Hack that has been applied to the current WIP ICS for Desire ROM. This is to keep you out of the development thread for the ICS ROM and keep it clean. Any questions should be asked in here and if anyone wants to develop it, go ahead. As mentioned many times in the original thread, they are not supporting this, so don't ask them! Funnily enough, neither am I, I am sick of reading questions pertaining to something that is mentioned every page as UNSUPPORTED.
http://www.youtube.com/watch?v=yZ6g-29pgwo
[ROM][Android 4.0.3][BETA]ICS for Desire by Sandvold[FULL HW+CAM preview][ALL HBOOTS]
Visualizzazione stampabile
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05-12-11, 09:57ChIP83
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05-12-11, 10:51Diavoletto
ok per l'accellerazione Hardware ci siamo..ma la MEmoria la vogliamo sistemare??? ce è impossibile usare un cellulare con quei pochi megabyte a disposizione..ce assurdo ho installato solo whatsapp e mi da problemi di memoria..eddaii :O
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05-12-11, 10:56ChIP83forse non avete capito che questa rom non è per il daily use, non è una versione stable ne tanto meno una beta, è un alpha.Quote:
Originariamente inviato da Diavoletto
L'A2SD+ sarà probabilmente una delle ultime cose che implementeranno, perché a nessuno interessa introdurre una funzione per avere spazio per le app su una rom test, funzione inoltre che può introdurre diversi problemi (ed aggiungere problemi o problemi non è certo il modo di risolverli). -
05-12-11, 12:44lavezzi
Comunque a fluidità sembra veramente ottimo!
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05-12-11, 12:54kintaxfuera
cmq io è quasi 2gg che la uso e non ho avuto neanche un impuntamento
Inviato dal mio HTC DESIRE ICS 4.0.1 usando Androidiani App -
05-12-11, 13:30noviz
Sono 2 giorni che la uso , a parte il problema della memoria nessun impuntamento, browser molto veloce ricezione e batteria ottimi.
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05-12-11, 13:50DiavolettoAnche x me idemQuote:
Originariamente inviato da noviz
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05-12-11, 14:51Jacopoandroid
Ragazzi leggendo tutto il thread ho notato che la ROM è molto funzionale pur essendo un Alpha e volevo chiedervi prima di mettere le mani sul mio desire come installarla, se potevate darmi delle delucidazioni sull'installazione grazie
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05-12-11, 14:55kintaxfuera
Si instilla come tutte le altre rom
Inviato dal mio HTC DESIRE ICS 4.0.1 usando Androidiani App -
05-12-11, 15:11JacopoandroidQuindi mi basta solo fare un full wipe e installarla da recovery?Quote:
Originariamente inviato da kintaxfuera
