ex11 - performance issues

[Joe Armstrong]

Brain dump 2

ex11 appears to be *faster* than kde for GUIs stuff - 

Experiment:

	1) Start top and ex11
	2) click on the "show file" demo
	3) zap the scrollbar up and down until I get 20% CPU load
	   for the X server
	4) Note the beam CPU usage

Results:
1) X server CPU c. 20% 
2) beam CPU usage c. 6%

        5) make a shell window the same size as the ex11 text window
        6) repeat step 3 in the shell

Results

1) X server CPU usage c. 20%
2) kdeinit CPU c. 10%

Conclusions:

	1) the X server is the bottleneck (easy to see)
	2) ex11 is faster than kde :-)

How can 2) be correct? I suspect the answer lies in some context switching or
locking that occurs in the C code.

  Interestingly,  the performance  of  X  is limited  by  the host  OS
context switching rate. So in sync mode I could do 4,500 request/sec
on my 400 MHz Celerion but 12,000 in async mode :-)


  Comments?

/Joe