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MPC5553/MPC5554 Microcontroller Reference Manual, Rev. 5
Freescale Semiconductor
10-45
Throughout the chapter, replaced “priority inversion” with “scheduling inefficiencies” as follows:
SECTION 10.5.5.1 Elevating Priority
From: "After they release the resource, they must lower
the PRI value in INTC_CPR to prevent further priority inversion."
To: "After they release the resource, the PRI value in INTC_CPR can be lowered."
From: "Using the PCP instead of disabling processor recognition of all interrupts reduces the priority inversion time when
accessing a shared resource."
To: "Using the PCP instead of disabling processor recognition of all interrupts eliminates the time when accessing a shared
resource that all higher priority interrupts are blocked."
SECTION 10.5.6 Selecting Priorities According to Request Rates and Deadlines
Added the acronyms RMS and DMS for ‘rate monotonic scheduling’ and ‘deadline monotonic scheduling.’
From: "Reducing the number of priorities does cause some priority inversion which reduces the processor's ability to meet its
deadlines. It also allows easier management of ISRs with similar deadlines that share a resource. They can be placed at the
same priority without any further priority inversion, and they do not need to use the PCP to access the shared resource"
To: "Reducing the number of priorities does reduce the processor's ability to meet its deadlines. However, it also allows easier
management of ISRs with similar deadlines that share a resource. They do not need to use the PCP to access the shared
resource."
SECTION 10.5.7.1 Scheduling a Lower Priority of an ISR
From: "Therefore, executing this later portion which does not need
to be executed at this higher priority can block the execution of ISRs which do not have a higher priority than the earlier portion
of the ISR but do have a higher priority than what the later portion of the ISR needs. This priority inversion reduces the
processor's ability to meet its deadlines."
To: "Therefore, executing this later portion which does not need
to be executed at this higher priority can prevent the execution of ISRs which do not have a higher priority than the earlier
portion of the ISR but do have a higher priority than what the later portion of the ISR needs. This preemptive scheduling
inefficiency reduces the processor's ability to meet its deadlines."
From: "This software settable interrupt request, which usually will have a lower PRIn value in the INTC_PSRn, therefore will
not cause priority inversion."
To: "This software settable interrupt request, which usually will have a lower PRIn value in the INTC_PSRn, therefore will not
cause preemptive scheduling inefficiencies."
SECTION 10.5.8 Lowering Priority within an ISR
From: "the only way (besides scheduling a task through an RTOS) to prevent priority inversion with an ISR whose work spans
multiple priorities"
To: "a way (besides scheduling a task through an RTOS) to prevent preemptive scheduling inefficiencies with an ISR whose
work spans multiple priorities"
From: "Therefore, the INTC does not support lowering the current priority within an ISR as a way to avoid priority inversion."
To: "Therefore, through its use of the LIFO the INTC does not support lowering the current priority within an ISR as a way to
avoid preemptive scheduling inefficiencies."
Corrected register name from EIISR to EISR in Interrupt Request Sources table.
Table 10-12. Changes to MPC5553/5554 RM for Rev. 4.0 Release (Continued)
Содержание MPC5553
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