Power Scripts for i8051 Synthesizable Model
Tuning Environment for i8051 Synthesizable Model
Introduction
One of the defining characteristics of embedded systems is that they
run one application for their entire execution time. This characteristic
creates a great potential for optimizations. For example, a general
purpose processor might have a datapath consisting of a register file,
ALU, and a shifter. For an instruction such as a move, this datapath is
expensive in terms of power because it must pass through the ALU and
shifter before being written back into the register file. If this move
operation was very common to a particular application, an optimization
could be made by modifying the register file to move data from one
location to another.
The information on this page describes an environment that simplifies
the process of tuning a microprocessor. Three main tools are provided in
order to analyze the power consumption of an 8051 microprocessor. The
first of these tools is an architectural view which generates a
hierarchical display of power consumption throughout the components of the
processor. The output is formatted so that it is readable by xdu, a
graphical program for displaying tree structures. The second tool
calculates the average power per instruction for the entire instruction
set (several jump instructions have not yet been implemented in this
tool). The third tool is an instruction set simulator which outputs a
program memory view that displays the instruction, power, and frequency
for every address. It also provides a data memory view that calculates
accesses for each location in ram.
ExampleAfter running the initial version of the 8051, we obtained
the following results: The table below shows a small sample of the
output of the instruction set power tool. The actual output shows results
for all instructions excluding several jumps which have not been
implemented yet. (Small sample of instruction set power, all
values are in mW)
ADDC_1
31.526465034965
ADDC_2
38.1159
ADDC_3
31.9229685314685
ADDC_4
43.3595
ADD_1
31.6965116550117
ADD_2
33.2728333333333
ADD_3
32.8297284382284
ADD_4
41.2952333333333The image below
shows the output from the architectural view tool. It can be seen that
U_RAM, U_ALU, U_CTR, and the buses for RAM and ROM are the most expensive
components. Xdu allows you to explore this hierarchy in much more detail
than is shown in the image. (Architectural view tool output
displayed in xdu, values are in 1/1000mW) src="Power Scripts for i8051 Synthesizable Model.files/xdu1.jpeg">
The table below displays output from the program memory view that
is provided by the instruction set simulation tool. For every location in
program memory, it displays the address, instruction, frequency of
execution, average power, and power * frequency. This view makes it easy
to determine which area of the program is the bottleneck in terms of power
consumption. (Small sample of program memory view, power is in
mW)
Addr
Ins
Freq
Pwr
Pwr*Frq
00727
XCH_1
15901
4.78177
76034.9
00728
XCH_1
15901
4.78177
76034.9
00729
RRC
15901
3.86277
61421.9
00730
XCH_1
15901
4.78177
76034.9
00731
INC_1
16474
3.90566
64341.9
00732
JNZ
16474
0
0A small sample of ram accesses are
shown below. It is obvious in this that the example most frequently
locations are the accumulator and psw. (Small sample of ram
location frequencies)
Addr
Freq
Type
00000
32557
RegBank0
00001
32334
RegBank0
00002
27461
RegBank0
00003
30042
RegBank0
00004
101096
RegBank0
00005
103961
RegBank0
00006
94789
RegBank0
00007
116525
RegBank0
00336
939913
PSW
00352
1003559
ACC
00368
11015
B
Installation Instructions(All files should be downloaded into
the same directory) 1) Download href="http://www.cs.ucr.edu/~dalton/i8051/i8051powerweb/i8051pwranalysis.tgz">i8051pwranalysis.tgz.2)
Download href="http://www.cs.ucr.edu/~dalton/i8051/i8051powerweb/xdu-3_0_tar">Xdu
for graphical tree representations. 3) Download href="http://www.cs.ucr.edu/~dalton/i8051/i8051powerweb/install.scr">install.scr.4)
Run install.scr.5) The sample output is located in the following
locations:Architectural view => ph_results/*.xduInstruction set
power => inspower.txtProgram memory view =>
iss_results/*.pmpData memory view => iss_results/*.ram
Execution Instructions1) In order to run all tools and generate a
report, run all.pl [version]. [Version] is used to print a version name on
the generated report. All scripts are located in the i8051pwranalysis
directory. 2) The xdu executable is in the xdu directory. It can be
used on all files in the i8051pwranalysis directory that have a .xdu file
extension. 3) href="http://www.cs.ucr.edu/~dalton/i8051/i8051powerweb/tools.html">Individual
tools and scripts are described in detail at this link.
