Add support for multi-threaded verilator

docs/Simulation/Software-RTL-Simulation.rst

@@ -181,3 +181,18 @@ An open-source vcd-capable waveform viewer is `GTKWave <http://gtkwave.sourcefor
 
 For a VCS simulation, this will generate a vpd file (this is a proprietary waveform representation format used by Synopsys) that can be loaded to vpd-supported waveform viewers.
 If you have Synopsys licenses, we recommend using the DVE waveform viewer.
+
+.. _sw-sim-verilator-opts:
+
+Additional Verilator Options
+-------------------------------
+
+When building the verilator simulator there are some additional options:
+
+.. code-block:: shell
+
+   make VERILATOR_THREADS=8
+
+The ``VERILATOR_THREADS=<num>`` option enables the compiled Verilator simulator to use ``<num>`` parallel threads.
+On a multi-socket machine, you will want to make sure all threads are on the same socket by using ``numactl``.
+You can also just use the ``numa_prefix`` wrapper, which is a simple wrapper around ``numactl`` that runs your verilated simulator like this: ``$(numa_prefix) ./simulator-<name> <simulator-args>``.