Multicore Settings
COMSOL Multiphysics supports two modes of parallel operation: shared-memory parallel operations and distributed-memory parallel operations, including cluster support. This section covers shared-memory processing, or multithreading, which is important for the performance of COMSOL Multiphysics computations. Some terms that are frequently used when describing multithreading are:
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Core: The core is a processor core used in shared-memory parallelism by a computational node with multiple processors.
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Speedup is how many times faster a job runs on N cores compared to 1 core, on a specific compute node. The speedup depends on the simulation type, the hardware used, and hardware drivers used.
In Windows, the default number of processor cores used by COMSOL Multiphysics is the total number of available physical cores. For example, if you have a 2 x dual core machine, 4 cores are used in parallel by a COMSOL Multiphysics process.
To find out how many processor cores your Windows machine has:
1
Start the Windows Task Manager (press Ctrl+Shift+Esc, or right-click the taskbar and select Task Manager in the context menu).
2
On the Performance page, click CPU. The number of cores can be seen as the number next to Cores.
If you want COMSOL Multiphysics to leave out one or more processor cores, you can set the number of cores used for a computational job in the Preferences window on the Computing > Multicore page (by first selecting the Number of cores checkbox and then entering the number of processor cores to use).
You can also change the default behavior of COMSOL Multiphysics by setting the environment variable COMSOL_NUM_THREADS to the desired number of cores. See the COMSOL Multiphysics Reference Manual for more information.