UNIX Filesystems: Evolution, Design, and Implementation

The Evolution of Multiprocessor UNIX

[WAIT87] documents the early years of Multi-Processor (MP) development in UNIX. In the mid 1980s the emergence of Sun Microsystems and Apollo Computing saw the introduction of cheaper workstations, allowing engineers to have their own workstations for the first time. In addition to the well-established computer companies such as DEC, IBM, and Cray, newcomers including Sequent, Alliant, Convex, and Encore started to introduce multiprocessor-based UNIX operating systems and hardware.

The first MP UNIX, named MUNIX, was developed at the Naval Postgraduate School in Monterey [HAWL75]. An MP-based UNIX kernel developed at Purdue University in the late 1970s ran on a VAX computer in a master/slave model whereby the UNIX kernel ran on one processor while user applications ran on the other processors. Within Bell Labs, the UNIX/370 project was formed to create an MP UNIX kernel to run on an MP version of the IBM 370 mainframe. This kernel used semaphores to lock various kernel structures. Members of the Bell Labs team then went on to create an MP UNIX to run on their own 3B20A resulting in a kernel that could perform 70 percent better than the UP version.

One company that would make enormous enhancements to SMP UNIX and that would eventually find its way into SVR4 ES/MP was Sequent Computers, which emerged in the mid 1980s and made significant improvements to both the underlying hardware and the UNIX kernel.

The large number of UNIX systems companies ...