[Qemu-devel] Attempt for reproducible behavior

[Alex-Uni <a_bulach@rbg.informatik.tu-darmstadt.de>]

Hello,

I am trying to modify Qemu, so it offers reproducible behavior. I'm 
using the icounts for the time measurement.
For example:
I have a simple code which measures the time before the start of a loop. 
The loop runs for an definite amount of rounds. In this case I let it 
count to 100000000 in a while-loop. Then the codes measures the time 
after the loop. Both times in milliseconds. The time difference is about 
5000 milliseconds.

Now, while the loop is still running, i make a snapshot. Lets say at 
2000 milliseconds.
After loading this snapshot it the loop should run for 3000 
milliseconds. But it doesnt, it's alway different.

I figured, that it depends on the value of next_tb and therefor on 
tcg_qemu_tb_exec(tc_ptr) in line 615 in the cpu-exec.c.

Now I have the problem, that I can't follow the code. I don't know why 
tcg_qemu_tb_exec(tc_ptr) produces different results
and where to look. I only found the define in the tcg.h.

Can somebody help me with this problem?
I'm working on the svn-version 5806.

Thank you
Alex
(Please CC: me when replying, I am not on the list)