Avago Technologies LSI53C1010 - Manual (Page 237)

SCSI SCRIPTS Processors 10-1
Chapter 10
Multithreaded I/O
This chapter describes multithreaded I/O and contains the following
sections:
•
Section 10.1, “Overview,” page 10-1
•
Section 10.2, “Multithreaded Operations Flow,” page 10-2
•
Section 10.3, “SCRIPTS Areas,” page 10-4
•
Section 10.4, “Multithreaded SCRIPTS Example,” page 10-4
•
Section 10.5, “Using the SIGP Bit to Abort an Instruction,”
page 10-10
•
Section 10.6, “I/O Completion,” page 10-12
10.1 Overview
The SCRIPTS processor allows multithreaded I/O operations with
minimal external processor intervention in systems that support
multitasking. Multithreaded algorithms must be used any time more than
one task is active in the system.
Figure 10.1 shows a situation where
multiple tasks are simultaneously accessing multiple devices. The path
between Task 1 and Disk 2 is highlighted to show how information might
be transferred. The device driver must schedule and control the I/O
requests based on such considerations as what devices are available
and the relative priorities of the requests.