eldo_user

Running Eldo
Multi-Threading Eldo Simulations
*** User : guest@machine
*** OS : Red Hat Enterprise Linux Client release 5.5 [VCO = ixl]
*** CPU :
Intel(R) Xeon(R) CPU
5130 @ 2.00GHz
Number of physical processors : 2
Hyper-Threading Technology : disabled
Number of cpu cores : 4
Number of logical processors : 4
*** Freq : 1995.089 MHz
*** Cache : 4096 KB
*** MEM : 4148040 kB
*** Date : Wed Oct 6 18:31:56 2010
When multi-threading is activated, the average number of threads used for the overall
simulation is printed at the end of the run.
Notes
• Thread-safe devices can be categorized as follows:
o
o
o
o
o
All MOSFET models are thread-safe except HVMOS and Mextram.
Verilog-A models are thread-safe when using the default Verilog-A flow.
Resistors, capacitors, diodes, and BJT models are thread-safe.
Sources and bias dependent objects are thread-safe.
User-defined models (UDM) are not thread-safe. If the model card leads to the
creation of access resistors, and if option NONWRMOS is specified, then the model
is not considered thread-safe.
• Using multi-threading is non-deterministic. Rounding can quickly accumulate because
floating-point computations suffer from rounding effects, and circuit simulators have to
perform millions of operations. With current hardware there is no way to guarantee
100% identical results when the arithmetic sequence changes. Multi-threading is one
case where the sequence of operations is not the same, and can therefore potentially
produce different results due to rounding.
• Multi-threading and DC computation
DC computation can be very sensitive to numerical noise (because of the algorithm
used), and as multi-threading cannot preserve the order of operations, it is possible to
obtain different DC computation times and even different DC solutions found from one
run to another. This can occur if the circuit has multiple valid DC points, and is the same
whether using multi-threading or not.
• Multi-threading and AC analysis
The part of the AC analysis related to matrix solving will be performed using multithreading.
The number of threads used is based on the number of operations that the
matrix solving requires and is dynamically computed. The number of threads cannot be
Eldo® User's Manual, 15.3 45