On Saturday, 28 June 2014 at 06:23:25 UTC, Paulo Pinto wrote:
Hi,
posting this talk here, as Java performance on Android is often
mentioned in the discussions about GC vs RC performance.
So here you have the Android team explaining:
- Dalvik GC sucks and is a basic stop the world implementation
with pauses > 10ms
- ART solves the GC issue by adopting multiple concurrent GC
algorithms,
depending on the application state thus reducing the stop down
to 3ms. More optimizations still to be done until the final
release
- JIT compiler optimized for battery life and low power
processors, thus only very hot methods get actually compiled to
native code
- Performance sorted out, by doing AOT compilation on install,
similar to approach taken by OS/400, Windows Phone 8
https://www.youtube.com/watch?v=EBlTzQsUoOw
--
Paulo
I like his focus on the duration of frames per second. If you are
aiming for 60FPS, you are aiming for a time period of about 16ms
to 17ms per frame. So he mentions the current Dalvik GC occupying
about 10ms for a collection in most cases, leading to a single
dropped frame, and a near full memory case leading to about 50ms
and above, leading to a few dropped frames. So when thinking
about optimising GC, aiming for a collection time small enough to
fit comfortably inside a frame seems like a good way to think
about it.
