Interrupts
An
interrupt
is a notification from a device that tells
the kernel that:
-
An action such as a disk transfer has been completed.
-
Data such as keyboard input or a mouse event has been received.
The kernel services an interrupt within the
context
of the current process that is running on the CPU.
The execution of the current process is suspended
while the kernel deals with the interrupt in system mode.
The process may then lose its place on the CPU
as a result of a context switch.
If the interrupt signaled the completion of an I/O transfer,
the scheduler wakes the process that was
sleeping on
that event,
and puts it on a run queue at a newly calculated numeric
priority.
It may or may not be the next process to run
depending on this priority.
Next topic:
Calculation of process priorities
Previous topic:
Preemption of a process that goes to sleep waiting for I/O
© 2003 Caldera International, Inc. All rights reserved.
SCO OpenServer Release 5.0.7 -- 11 February 2003