Hardware Considerations

This chapter describes the enhancements made to OS/2 Version 2.0 in the area of hardware support. We begin by focusing on the I/O-related components of the operating system which are collectively known as the I/O supervisor. Later in this chapter we investigate IBM and OEM hardware support. The changes in OS/2 Version 2.0 are specifically targeted to optimize disk device requests through improvements to the High Performance File System (HPFS) and FAT file system drivers, and to make use of the capabilities of the new SCSI adapters and disks. Figure "OS/2 Version 2.0 I/O Related Components" provides an overview of the I/O related components of OS/2 Version 2.0.

The enhancements in the I/O supervisor result in:

Improved overall system I/O throughput capability by:

Using new protocol and data structures designed to optimize the submission of I/O requests
Allowing I/O command chaining by permitting file systems to submit a list of I/O operations to the device driver rather than submitting them one at a time
Providing a high-performance mechanism for transferring data to and from buffers for which pages are physically discontiguous in real storage
Providing reductions in the overhead of interrupt processing and I/O request completion

An architected and effective set of interfaces for an Installable File System (IFS) to allow paging I/O requests to be managed by a File System Driver (FSD).

The remainder of this chapter will discuss device driver and file system changes made under OS/2 Version 2.0, and IBM and OEM hardware support.

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