Embedded Software for SoC - Grupo de Mecatrônica EESC/USP

Software Architectural Transformations 481
Table 34-1. Experimental results showing the energy impact of software architectural
transformations.
Example
Original
Energy
(mJ)
# proc
# ipc
Optimized
Energy
(mJ)
# proc
# ipc
% Energy
reduction
Aware
Headphone
Vcam
Climate
Navigator
ATR
12.956
1.668
1.572
0.239
1.659
6.940
8
6
4
4
5
4
11
8
5
5
7
7
8.204
1.461
1.375
0.081
1.456
6.199
7
3
2
2
3
3
9
2
1
1
3
4
36.7%
12.4%
12.5%
66.1%
12.2%
10.7%
sents the initial software architecture for this program is shown in Figure
34-11(a). Explanation of the annotations in the figure were provided in Section
3.2. For the purpose of illustration, we consider this program to execute under
the embedded Linux OS. Edges coming from the hardware devices (indicated
as empty square boxes) indicate the data flow from the devices to the
application processes, and are implemented using read() system calls in
Linux. Some of these reads are blocking, indicated by a small square box at
the tip of the arrow.
The initial software architecture program code is written in C. The energy
consumption statistics of this program are obtained by running it in the energy
simulation framework EMSIM [24]. Under the initial software architecture,