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miniXyce circuit/network simulation mini-application
--------------------------------------
Contents of this README file:
1. miniXyce overview
2. miniXyce versions
3. building miniXyce
4. running miniXyce
5. generating test circuits
6. understanding the results
--------------------------------------
--------------------------------------
1. miniXyce overview
At this time, miniXyce is a simple linear circuit simulator with a
basic parser that performs transient analysis on any circuit with
resistors (R), inductors (L), capacitors (C), and voltage/current
sources. The parser incorporated into this version of miniXyce is a
single pass parser, where the netlist is expected to be flat
(no hierarchy via subcircuits is allowed). Simulating the system of
DAEs generates a nonsymmetric linear problem, which is solved using
un-preconditioned GMRES. The time integration method used in miniXyce
is backward Euler with a constant time-step. The simulator outputs
all the solution variables at each time step in a 'prn' file.
The development of the first version of miniXyce resulted in something
closer to a compact application than a miniapp since more focus was put
on the simulator returning the correct answer, than modeling performance
characteristics of interest. Further analysis of Xyce has called out
particular performance issues in each of the three phases of circuit
simulation: parsing, device evaluation/loading, and the solution of linear
equations. These issues will inspire enhancements to, and a second version
of, miniXyce.
Finally, miniXyce compares the computed solution against gold standard output
from Xyce for a couple test circuits found in the 'tests' directory.
--------------------------------------
2. miniXyce versions:
- miniXyce_ref:
reference version: self-contained, includes serial and MPI-parallel
parallelism is optional, it can be built without MPI usage.
-------------------
3. Building miniXyce:
The default case is: cd into the 'miniXyce_ref' directory and type 'make'.
That will build the MPI-parallel miniXyce code assuming you have the
mpi-compiler-wrappers mpicxx in your path.
If successful, that will create an executable called miniXyce.x.
Special builds can be done for things like:
- gnu compilers (g++), no MPI
type 'make -f Makefile.gnu.serial'
- Intel compilers (icpc), no MPI
type 'make -f Makefile.intel.serial'
If the default makefile isn't correct for your system, copy and edit and
use a 'make -f' command similar to the above cases.
Note 1:
'make' calls the script 'generate_info_header' to generate miniXyce_info.hpp
with platform and build information. If that script fails for some reason and
doesn't produce a valid miniXyce_info.hpp header, you can still build miniXyce by
typing
'make MINIXYCE_INFO=0'.
-------------------
4. Running miniXyce:
miniXyce can be run like this:
% <mpi-run-command> miniXyce.x <options>
Description of command line options:
-c, --circuit {filename}: specifies the netlist to be simulated.
-ti, --tstart, --t_start {double value}: specifies start time of transient simulation
-tf, -- tstop, --t_stop {double value}: specifies stop time of transient simulation
-h, --tstep, --t_step {double value}: specifies the length of each transient simulation time step
-tol, --tolerance {double value}: specifies the GMRES tolerance
-k, --restart {double value}: tells GMRES how often to restart
-i, --init, --init_cond, --initcond, --x0 {vector of length (num_nodes + num_voltage_sources + num_inductors)}:
specifies the initial condition for the simulation. If it is not specified, then a DC operating point initial condition is assumed.
-pf, --paramsfile, --params_file {filename}: specifies a file from which additional simulation parameters are to be obtained.
--prev : this flag tells the simulator to use whatever parameter values it used last time (for those parameters that have not been specifies on the command line)
miniXyce examples:
Ex 1: Run a simulation of circuit tests/cir1.net on 3 processors, using t_start = 1e-6 and other parameters taken from the file params.txt
mpirun -np 3 miniXyce.x --circuit tests/cir1.net --t_start 1e-6 --pf params.txt
Ex 2: Repeat the above simulation, but this time with 4 processors
mpirun -np 4 miniXyce.x --prev
Ex 3: Simulate the circuit cir4.net on 2 processors with default parameters
mpirun -np 2 miniXyce.x -c tests/cir4.net
Ex 4: Repeat the above simulation, but this time use an initial condition [2 3]
mpirun -np 2 miniXyce.x --prev --init 2 3
Note: The initial condition is *not* saved in the last_used_params.txt file. Only the rest of the parameters are saved.
So if you use --prev without specifying anything else, a DC operating point initial condition will be computed.
-----------------
5. Generating test circuits:
The test circuits provided in the 'tests' directory (cir1.net, cir2.net, cir3.net, and cir4.net) can run on, at most, 4 MPI processes.
To make it easier to generate netlists for RC and RLC Ladders, there are 2 perl scripts RC_Ladder.pl and RLC_Ladder.pl in the 'tests'
directory. You can use them as follows:
perl RC_Ladder.pl <number of RC Ladder stages you want> ><circuit name>.net
perl RLC_Ladder.pl <number of RLC Ladder stages you want> ><circuit name>.net
Example: perl RC_Ladder.pl 5 >cir6.net
This allows the user to generate arbitrarily large linear circuits to test miniXyce.
-----------------
6. Understanding the results
After running miniXyce, you will be left with a text file named <ckt_name>_tran_results.prn. There will only be one, regardless of the number of processors.
The first line of this file is of the form:
TIME state_variable_name_1 state_variable_name_2 ... state_variable_name_k
Each subsequent line in each of these files gives values of the form:
time value1 value2 ... valuek
where value1 ... valuek are all the components of the solution vector x.
In addition, each line of the text file will contain two more attributes corresponding to the number of gmres iterations and restarts respectively.
Matlab can be used to plot the data in this file using the very basic plot_tran_sim_results.m, which can be found in the 'utils' directory.