Architectural Design Objectives

The architectural design objectives for a multiprocessor (MP) version of OS/2 were as follows:

  • Transparent support for two or more CPUs (16 CPUs max).

  • Support for applications and device drivers which are not MP safe and aware.

  • Support for various MP hardware platforms (eg. Compaq, APIC, EBI2, Corollary, etc) via a Platform Specific Driver (PSD) layer.

  • Small footprint - 4MB for OS/2 and DOS applications; 6MB for WINOS2

  • Performance equal to or better than Windows NT.

  • 100% application compatible for existing OS/2 DOS and Windows applications.

  • Honor priority preemption across all processors.

    Transforming the OS/2 2.x uniprocessor (UP) code base into OS/2 for SMP V2.11 was mostly a matter of copying the vital system data structures for the number of processors. Only ONE copy of OS/2 is running at one time, no matter how many processors are present. System initialization automatically determines the number of processors and generates the appropriate number of data structures, including new control blocks and per-processor data structures. one process/thread running

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