In the end, you will always have to write to non-cached memory or flush the cache to get it to the device. There should be no performance penalty in page flipping, but a performance increase. You should also have a smaller memory footprint.
The typical reason for poor performance of page flipping is the driver having a bad implementation of waiting for the frame sync (to eliminate flicker) or trying to do some sort of smooth scrolling. Either of these things could slow down drawing. It should be nearly instantaneous when done right. One thing you might look at is cpu usage. If CPU usage is low and drawing is slow, then waiting on sync could very well be the issue. Cheers, Sean Alexey Roslyakov wrote: > Michael, > I tried to implement page flipping in s3c2410fb. No luck. Performance > is worse than in case without flipping. > I suppose SurfaceFlinger uses memcpy (or similar) for double buffering > from/to "offscreen" surface(s). > If offscreen surface resides in Fb memory it's non-cached, therefore > performance suffer. > (I may be wrong. But it's most credible explanation I found) > > On 4 дек, 15:30, Michael Trimarchi <[email protected]> wrote: > >> Hi, >> >> Alexey Roslyakov wrote: >> >>> Thanks, Michael, >>> great work. >>> >>> Now bionic code (libc/arch-arm/*.s) is armv4-friendly. You can safely >>> use original bionic/libc/Android.mk - optimized versions of memcpy, >>> strlen and memcmp. >>> Android will run faster a little bit;) >>> >> I have redone a rebase and use now the memcpu of bionic but with same >> result in >> performance. I will continue to investigate but I think that it can be >> related >> to the new graphics abstraction. I have compiled alsa, but it is far away >> to work. Have you done some work on it? >> >> Michael >> >> >>> On 27 , 03:25, Michael Trimarchi <[email protected]> >>> wrote: >>> >>>> Hi, >>>> >>>> this is my patch to boot android. The PAN display ioctl is only for >>>> openmoko, hope that can help >>>> some user. >>>> >>>> The overall performance are not good but the keyboard is three time faster >>>> from cupcake version :) >>>> >>>> Michael >>>> >>>> eclair.patch >>>> 50K >>>> > > -- unsubscribe: [email protected] website: http://groups.google.com/group/android-porting
