Architecture-learning of interruption shielding
When learning the architecture of the system, there are two points that I have never understood. One is floating point processing, the other is shielding interruption, and the floating point processing is not understood so far. The shielding interruption is somewhat enlightened.
Shielding code: the shielding code between 1 and 0 is different from that between 0 and 0.
Interrupted instance:
1. All interruptions arrive at the same time:
1. Examples in the book:
1) interrupt response priority: D1> D2> D3> D4
2) interrupt handling priority: D1> D2> D3> D4
3) interrupt response and handling process:
4) interrupt time analysis: assume that the interrupt response time is 1 s and the interrupt processing time is 4 s, the line segment AB is 5 s, including the interrupt response and interrupt processing processes, if the line segment CD is 0 s, the original program is returned.
2. Change the instance
1) interrupt response priority: D1> D2> D3> D4
2) interrupt handling priority: D4> D3> D2> d1
3) interrupt response and handling process:
4) interrupt time analysis: assume that the interrupt response time is 1 s, the interrupt processing time is 4 s, the line segment AB is 1 s, the line segment CD is 4 S, and the line segment EF is 5 s.
3. Change again:
1) interrupt response priority: D1> D2> D3> D4
2) interrupt handling priority: D1> D4> D3> D2
3) interrupt response and handling process:
4. Interrupt Time Analysis: If the interrupt response time is 1 s and the interrupt processing time is 4 s, the BC is 0 s long and the De is 1 s long.
Summary: The image must meet four partial order relationships.
1. Meeting the interrupt response priority: Da> dB> DC> dd
2. the interrupt handling priority is met: DX> dy> dz> dk
3. All interrupt responses are met before the interrupt handling.
4. If a's response and processing priority are prior to B, A's processing time must be prior to B's response time. (The reason for delay cannot be found because everything takes precedence)
Nature: If all interruptions arrive at the same time, the interrupted graph is unique.
Proof: we will prove this nature later.
Q & A: In the interrupt shield table, all the interrupt shield codes are blocked from the top left to the bottom right.
Cause: because of the same priority, there is no need to interrupt the original priority program. From then on, we can conclude that:
1. There are programs blocking all programs.
2. There is no program that opens all programs. (Because it cannot be enabled for the same priority)
D1 D2 D3
D1 shielding
D2 shielding
D3 shielding
2. Non-simultaneous arrival of interrupted requests
1. brief excerpt from the question:
1) interrupt response priority: D1> D2> D3> D4> D5 (priority response program for simultaneous handling)
2) interrupt handling priority: D4> D5> D3> D2> d1 (handling the Response Program of the running program)
3) assume that the duration from the time when the processor responds to the interrupt service request from the interrupt source to the time when the first interrupt is started in the interrupted service program is a unit of time, the time used by the processor to run other parts of the interrupted service program is four units of time. When the processor executes the main program, the source D3, D4, and D5 are interrupted at the same time. After three units of time, the source D1 and D2 are interrupted at the same time. The modified interrupt shielding code is used to draw out the process of the processor responding to the interrupt service request from each interrupt source and actually running the interrupt service program.
4) interrupt response and handling process:
2. Question requirements:
1) interrupt response priority: D1> D2> D3> D4
2) interrupt handling priority: D3> D2> D4> d1
3) when running the main program, there are two requests, D1 and D2. when running the interrupt source D2, there are two service interruption requests, D3 and D4, and the service interruption program is drawn.
Conclusion: At the same time, the response priority is high first, and the response priority is high during execution. If there are multiple response priorities, the response priority is high first.
