[GCJ] Performance of GUI applications on embedded systems

[Andrew Haley]

ffileppo wrote:
>>>> Here's one improvement.  If you can get rid of the places in the GTK peers
>>>> where class and method lookups are performed at runtime you'll probably
>>>> have a fix.  This shouldn't be a massive amount of work, just rather
>>>> boring.
>>>>
>>>> In gcj,
>>>>
>>>>   * Compiled java code is quite fast.
>>>>   * Class lookup by name is slow.
>>>>   * Calling JNI code from compiled java code is quite fast.
>>>>   * Calling compiled java code from JNI code is slow.
>>>>   * Exceptions are slow.
>>> I'm testing your patch on my embedded system and now I can see that GUI performance are very much better (particularly during application startup).
>>>
>>> Thank you so much!
>>>
>>> However running my test case (please see my first post) I see that CPU usage is always at 100% (after the application is running),
>>> so the responsiveness is still not very good.
>> What do you expect?  You're setting up a Timer with a delay of
>> 0 milliseconds between events, and it's running continuously.
>>
>> Andrew.
>>
> 
> You're right.
> However I'm experiencing slowness when testing some other GUI sample application (e.g. the test case attached at the end).
> 
> In this particular test case, the application takes a lot of time to startup (compared to the same device, running WinCE and CrEme JVM) and during start up the CPU usage is always at 100%.
> 
> After startup, I'v also noticed that highlighting and/or clicking a certain number of times on buttons cause the application to hang and after that the CPU usage is always 100%.

I've identified some serious GTK locking problems with this version of gcj.

I'm investigating.

Andrew.