RTEMS Hewlett Packard PA-RISC Applications Supplement
The maximum period with traps disabled or the processor interrupt level set to it's highest value inside RTEMS is less than RTEMS_MAXIMUM_DISABLE_PERIOD microseconds including the instructions which disable and re-enable interrupts. The time required for the HP-7100 to vector an interrupt and for the RTEMS entry overhead before invoking the user's trap handler are a total of RTEMS_INTR_ENTRY_RETURNS_TO_PREEMPTING_TASK microseconds. These combine to yield a worst case interrupt latency of less than RTEMS_MAXIMUM_DISABLE_PERIOD + RTEMS_INTR_ENTRY_RETURNS_TO_PREEMPTING_TASK microseconds at 15 Mhz. [NOTE: The maximum period with interrupts disabled was last determined for Release RTEMS_RELEASE_FOR_MAXIMUM_DISABLE_PERIOD.]
It should be noted again that the maximum period with interrupts disabled within RTEMS for the HP-7100 is hand calculated.
RTEMS Hewlett Packard PA-RISC Applications Supplement
Copyright © 1988-1998 OAR Corporation