The developers of the ReactOS operating system, aimed at ensuring compatibility with Microsoft Windows programs and drivers, announced the readiness of an initial set of patches for loading the project on multiprocessor systems with SMP enabled. Changes to support SMP have not yet been included in the main ReactOS codebase and need to be improved, but the very fact of being able to boot with SMP mode enabled is noted as an important achievement in the development of the project (until now, one of the significant limitations of ReactOS was the use of only one CPU core in the process ).
Work on the implementation of SMP in ReactOS had a positive impact on the overall stability of the system, as it made it possible to identify and eliminate many related errors in the code related to handling locks and parallelizing process execution. Associated changes also mention the ability to launch the task manager from Windows XP to display the load on the processors.
Source: opennet.ru