eldo_user

Running Eldo
Multi-Threading Eldo Simulations
• The machine is a multi-CPU machine.
• The circuit contains devices which are thread-safe.
Eldo automatically computes if launching multi-threading is advantageous regarding the overall
device evaluation time. If it takes more time to wake-up the threads than computing the device
evaluations in one thread, then only one thread will be used.
If the circuit does not contain any thread-safe devices, multi-threading is ignored. Eldo provides
a notification when it cannot apply thread optimization on models, handles them in a single
processor. Thread-safe and non-thread-safe models can be used in the same circuit. See “Notes”
on page 45 for further information on thread-safe devices.
Eldo automatically adjusts the number of threads, and so the number of CPUs used, to minimize
the computation time. Eldo detects when other processes compete for resources, and decreases
the number of CPUs used if it will reduce computation time. Eldo also attempts to detect when
busy resources become available in order to use them. Eldo will never try to use more resources
than what has been specified with the -use_proc argument.
Note
Because this algorithm is always active, Eldo might use less threads than specified even on
a computer with no other active processes. The main purpose of the algorithm is to select the
number of threads that leads to the best performance; sometimes fewer is better.
Example Transcripts
When multi-threading is activated, the CPU time reported by Eldo is the sum of the CPU time
of all threads. This time will be much higher than the global elapsed time reported by Eldo. The
below example is an extract of a transcript showing this:
# ----- Summary run statistics ----
# Global Threads cpu Time 72h 27mn 31s 620ms
# Global Elapsed Time 47h 36mn 21s
Eldo prints information about the machine used for simulation including: clock frequency, the
number of cores, the number of threads used, and so on. Example output:
***** SYSTEM INFORMATION ...
44
Eldo® User's Manual, 15.3