Multiprocessing & MailSite MailSite software takes advantage of multiprocessing and multithreading capable hardware and software systems. By using a multiprocessing server the system is able to divide the resource request (load) evenly over the multiple CPUs. For example a system running a single CPU might utilize an 80% resource usage level. However, if you run two CPUs the resource request should be 40% divided over both CUPs. MailSite takes advantage of multiprocessing system and divides the load equally over the multiple CPUs. To verify MailSite is multiprocessing: 1. Bring up Windows Performance Monitor 2. Display the two CPUs 3. View the resources level 4. Turn on or off the multiple CPUs 5. The resource level will increase or decreass on all CPUs Note: MailSite does not take advantage of the Process Affinity option which allows you to manually assigning services to each processor. Definition of Multiprocessing: Multiprocessing is the coordinated processing of programs by more than one computer processor. Multiprocessing is a general term that can mean the dynamic assignment of a program to one of two or more processors working in tandem or can involve multiple computers working on the same program at the same time (in parallel).

With the advent of parallel processing, multiprocessing is divided into symmetric multiprocessing (SMP) and massively parallel processing (MPP).

SMP (symmetric multiprocessing) is the processing of programs by multiple processors that share a common operating system and memory. In symmetric (or "tightly coupled") multiprocessing, the processors share memory and the I/O bus or data path. A single copy of the operating system is in charge of all the processors. SMP, also known as a "shared everything" system, does not usually exceed 16 processors.

Resources:
http://whatis.techtarget.com/ (note: search on multiprocessing & SMP)