Download Using virtualization to enforce real-time Thesis

Diploma Thesis
54
E
-0
1
1,00
8,
0,90
0,80
0,70
0,60
0,50
0,40
-0
5
61
E
7,
E
8,
07
0M
[
[1
M
,1
M
,1
K
00
[1
,1
0K
[1
[
2,
K[
00
0K
,1
K
[1
,1
00
[1
[
K[
0[
10
0,
[1
49
-0
3
-0
3
E
39
3,
0,
0[
,1
[0
Figure D-2:
E
-0
2
6,
00
E
0,10
57
+0
0
E
0,20
0,00
-0
2
0,30
Distribution of the influence on Fedora without virtualization, worst case
On the best case, bound95% = 100 ticks = 44.1 ns, exactly the same as on Xenomai. In this
case, the test process was obviously very rarely de-scheduled by the Linux scheduler.
On the worst case, bound95% = 1 million ticks = 441 µs, which means that if a process wants
to execute, it may have to wait for an execution up to 441 µs on this system. Of course this
value is just an order of magnitude.
The variation between the best case and the worst case is really significant, whereas both
experiments have been made in the same conditions. How can later variations induced by
the virtualization level be detected if the reference test is so unstable?
Moving the mouse during the test for example can make the results even worse, which is not
the case on Xenomai.
A-14
Diploma Thesis-RT&Virtualization-V1.0/30.04.2010
© KIT and COMSOFT