- Contexts 3 6 1 – Fast Window Switcher Diagrams
- Contexts 3 6 1 – Fast Window Switcher Diagram Unlabeled
- Contexts 3 6 1 – Fast Window Switcher Diagram System
Contexts 3 6 1 – Fast Window Switcher Diagrams
2012 F150 Fuse Diagrams
These diagrams show the fuse and relay locations, layout, a descriptions for a 2012 F150 Fuse
Note: By the way, if you do have to replace the ignition switch, don't use any tools to remove the padded batwing horn 'button'. Just use fingers to pull each of the four corners off. To test the ignition switch - Jim recommended simply running a temporary wire from Fuse #12 to the (+) terminal on the coil. Busy context dependency relationships are determined at the point the first busy state is added. If the DOM node is re-parented after a busy context was added, the context will maintain dependencies with any parent DOM contexts. The application logic creating busy states is responsible for ensuring these busy states are resolved. Contexts is a radically faster and simpler window switcher. It gives you 4 ways to switch windows: Switch with one click to any window: An auto-hiding sidebar shows your windows organized in groups. To switch to a window just click its title in the list. It is as simple as that. Steady OFF Steady ON Fast Flash 1 flash 2 flashes 3 flashes 4 flashes 5 flashes 6 flashes 7 flashes Internal control fault or no power Normal operation, no call for heat Normal operation, call for heat present Pressure switch does not close within 30 seconds of inducer energized.
The 2012 F150 Fuse panel is located under the right-hand side of the instrument panel. To remove the trim panel for access to the fuse box, pull the panel toward you and swing it out away from the side and remove it. To reinstall it, line up the tabs with the grooves on the panel, then push it shut. To remove the fuse box cover, press in the tabs on both sides of the cover, then pull the cover off. To reinstall the fuse box cover, place the top part of the cover on the fuse panel, then push the bottom part of the cover until you hear it click shut. Gently pull on the cover to make sure it is seated properly.
Fuse/Relay Location – Fuse Amp Rating – Protected Circuits
1. 30A Driver side front window
2. 15A SYNC0002
3. 30A Passenger side front window
4. 10A Interior lamps
5. 20A Memory module
6. 5A Not used (spare)
7. 7.5A Power mirror switch, Memory seatmodule
8. 10A Not used (spare)
9. 10A Radio display, GPS module,Navigation display
10. 10A Run/accessory relay
11. 10A Instrument cluster
12. 15A Interior lighting, Puddle lamps, Back lighting, Cargo lamp
13. 15A Right turn signals/stop lamps
14. 15A Left turn signals/stop lamps
15. 15A Reverse lights, High-mounted stop lamp
16. 10A Right low-beam headlamp
17. 10A Left low-beam headlamp
18. 10A Brake-shift interlock, Keypad illumination, PCM wakeup, PATS
19. 20A Audio amplifier
20. 20A Power door locks
21. 10A Ambient lighting
22. 20A Horn
23. 15A Steering wheel control module
24. 15A Datalink connector, Steering wheel control module
25. 15A Not used (spare)
26. 5A Radio frequency module
27. 20A Not used (spare)
28. 15A Ignition switch
29. 20A Radio/Navigation
30. 15A Front parking lamps
31. 5A BOO – IP, BOO – Engine
32. 15A Delay/accessory – moon roof, power windows, locks, Automatic dimming mirror/Compass
33. 10A Heated seats
34. 10A Reverse sensing system, 4×4 switch, Rear video, Off road indicator (SVT Raptor)
35. 5A Hill descent switch (SVT Raptor)
36. 10A Restraint control module, Occupant classification system module
37. 10A Trailer brake control
38. 10A Delayed accessory – 110V power point, Radio (AM/FM)
39. 15A High beam headlamps
40. 10A Rear park lamps
41. 7.5A Passenger airbag deactivation indicator, Upfitter switch (SVT Raptor)
42. 5A Overdrive cancel switch
43. 10A Not used (spare)
44. 10A Not used (spare)
45. 5A Not used (spare)
46. 10A Climate controls module
47. 15A Fog lamps, Exterior mirror turn signals
48. 30A Circuit Breaker Power rear windows, Power sliding back window
49. Relay Delayed accessory
2012 F150 Fuse Panel Engine Bay Power Distribution Box
The power distribution box is located in the engine compartment. The power distribution box contains high-current fuses that protect your vehicle's main electrical systems from overloads.
Fuse/Relay Location – Fuse Amp Rating – Protected Circuits
1. — Power train control module (PCM) relay (3.7L, 5.0L and 6.2L engines)
2. — Starter relay
3. — Blower motor relay
4. — Rear window defroster relay
5. — Electric fan relay (high speed)
6. — Trailer tow (TT) park lamp relay
7. — Run/start relay
8. — Fuel pump relay
9. — TT Battery charger relay
10. — PCM relay (3.5L engine)
11. 30A** Power running board motors
12. 40A** Electric fan 50A** Electric fan (6.2L with max trailer tow, SVT Raptor)
13. 30A** Starter relay power Roadside Emergencies
14. 30A** Passenger power seat
15. 40A** Electric fan 50A** Electric fan (6.2L with max trailer tow, SVT Raptor)
16. — Not used
17. 30A** Trailer brake control
18. 30A** Upfitter 1 (SVT Raptor)
19. 30A** Upfitter 2 (SVT Raptor)
20. 20A** 4×4 module (electronic shift)
21. 30A** TT battery charge relay power
22. 20A** Cigar lighter
23. — A/C clutch relay
24. — Not used
25. — Vacuum pump relay (3.5L engine)
26. 10A* PCM – keep alive power, PCM relay coil, canister vent solenoid (3.7L, 5.0L and 6.2L engines)
27. 20A* Fuel pump relay power
28. 10A* Upfitter 4 (SVT Raptor)
29. 10A* 4×4 IWE solenoid
30. 10A* A/C clutch
31. 15A* Run/start relay power
32. 40A** Rear window defroster relay power, Heated mirror relay power
33. 40A** 110V AC power point
34. 40A** PCM relay power (3.7L, 5.0L and 6.2L engines) 50A** PCM relay power (3.5L engine)
35. — Not used
36. 30A** Roll stability control (RSC)/Anti-lock brake system (ABS)
37. — TT left stop/turn relay
38. — TT right stop/turn relay
39. — TT back-up lamps relay
40. — Electric fan relay
41. 15A* Front camera washer (SVT Raptor)
42. 5A* Run/start coil
43. 15A* TT back-up lamp relay power
44. 15A* Upfitter 3 (SVT Raptor)
45. 10A* Alternator sensor (non-6.2L engines)
46.10A* Brake on/off (BOO) switch
47. 60A** RSC/ABS module
48. 20A** Moon roof
49. 30A** Wipers
50. — Not used
51. 40A** Blower motor relay power
52. 5A* Run/start – Electronic power assist steering, Blower relay coil
53. 5A* Run/start – PCM
54. 5A* Run/start – 4×4 module, Back-up lamps, RSC/ABS, TT battery charge relay coil, Rear window defroster relay coil, Front camera washer relay coil (SVT Raptor)
55. — Not used
56. 15A* Heated mirrors
57. — Not used
58. — Not used
59. — Not used
60. — Not used
61. — Not used
62. — Wiper motor relay
63. 25A** Electric fan
64. 40A** Vacuum pump relay power (3.5L engine)
65. 20A** Auxiliary power point (instrument panel)
66. 20A** Auxiliary power point (inside center console)
67. 20A** TT park lamps relay power
68. 25A** 4×4 module
69. 30A** Passenger heated/cooled seats
70. — Not used
71. 20A** Heated rear seats
72. 20A** Auxiliary power point (Rear)
73. 20A** TT stop/turn lamps relay power
74. 30A** Driver power seat/memory module
75. 15A* PCM – voltage power 1 (3.7L, 5.0L, 6.2L engines PCM module) 25A* PCM – voltage power 1 (3.5L engine PCM module)
76. 20A* PCM – Voltage power 2 (General power train components, Mass air flow/Intake air temp sensor) (3.7L, 5.0L, 6.2L engines) 20A* PCM – Voltage power 2 (General powertrain components, Canister vent solenoid) (3.5L engine)
77. 10A* PCM – Voltage power 3 (Emission related power train components, Electric fan relays coil)
78. 15A* PCM – Voltage power 4 – Ignition coils (3.5L, 3.7L, 5.0L engines) 20A* PCM – Voltage power 4 – Ignition coils (6.2L engine)
79. 5A* Rain sensor
80. — Not used
81. — Not used
82. — Not used
83. — Not used
84. — Not used
85. — Electric fan relay (low speed)
In computing, a context switch is the process of storing the state of a process or thread, so that it can be restored and resume execution at a later point. This allows multiple processes to share a single central processing unit (CPU), and is an essential feature of a multitasking operating system.
The precise meaning of the phrase 'context switch' varies. In a multitasking context, it refers to the process of storing the system state for one task, so that task can be paused and another task resumed. A context switch can also occur as the result of an interrupt, such as when a task needs to access disk storage, freeing up CPU time for other tasks. Some operating systems also require a context switch to move between user mode and kernel mode tasks. The process of context switching can have a negative impact on system performance.[1]:28
Cost[edit]
Context switches are usually computationally intensive, and much of the design of operating systems is to optimize the use of context switches. Switching from one process to another requires a certain amount of time for doing the administration – saving and loading registers and memory maps, updating various tables and lists, etc. What is actually involved in a context switch depends on the architectures, operating systems, and the number of resources shared (threads that belong to the same process share many resources whether compared to unrelated non-cooperating processes. For example, in the Linux kernel, context switching involves switching registers, stack pointer (it's typical stack-pointer register), program counter, flushing the translation lookaside buffer (TLB) and loading the page table of the next process to run (unless the old process shares the memory with the new).[2][3] Furthermore, analogous context switching happens between user threads, notably green threads, and is often very lightweight, saving and restoring minimal context. In extreme cases, such as switching between goroutines in Go, a context switch is equivalent to a coroutine yield, which is only marginally more expensive than a subroutine call.
Switching cases[edit]
There are three potential triggers for a context switch:
Multitasking[edit]
Contexts 3 6 1 – Fast Window Switcher Diagram Unlabeled
Most commonly, within some scheduling scheme, one process must be switched out of the CPU so another process can run. This context switch can be triggered by the process making itself unrunnable, such as by waiting for an I/O or synchronization operation to complete. On a pre-emptive multitasking system, the scheduler may also switch out processes that are still runnable. To prevent other processes from being starved of CPU time, preemptive schedulers often configure a timer interrupt to fire when a process exceeds its time slice. This interrupt ensures that the scheduler will gain control to perform a context switch.
Interrupt handling[edit]
Modern architectures are interrupt driven. This means that if the CPU requests data from a disk, for example, it does not need to busy-wait until the read is over; it can issue the request (to the I/O device) and continue with some other task. When the read is over, the CPU can be interrupted (by a hardware in this case, which sends interrupt request to PIC) and presented with the read. For interrupts, a program called an interrupt handler is installed, and it is the interrupt handler that handles the interrupt from the disk.
Cost[edit]
Context switches are usually computationally intensive, and much of the design of operating systems is to optimize the use of context switches. Switching from one process to another requires a certain amount of time for doing the administration – saving and loading registers and memory maps, updating various tables and lists, etc. What is actually involved in a context switch depends on the architectures, operating systems, and the number of resources shared (threads that belong to the same process share many resources whether compared to unrelated non-cooperating processes. For example, in the Linux kernel, context switching involves switching registers, stack pointer (it's typical stack-pointer register), program counter, flushing the translation lookaside buffer (TLB) and loading the page table of the next process to run (unless the old process shares the memory with the new).[2][3] Furthermore, analogous context switching happens between user threads, notably green threads, and is often very lightweight, saving and restoring minimal context. In extreme cases, such as switching between goroutines in Go, a context switch is equivalent to a coroutine yield, which is only marginally more expensive than a subroutine call.
Switching cases[edit]
There are three potential triggers for a context switch:
Multitasking[edit]
Contexts 3 6 1 – Fast Window Switcher Diagram Unlabeled
Most commonly, within some scheduling scheme, one process must be switched out of the CPU so another process can run. This context switch can be triggered by the process making itself unrunnable, such as by waiting for an I/O or synchronization operation to complete. On a pre-emptive multitasking system, the scheduler may also switch out processes that are still runnable. To prevent other processes from being starved of CPU time, preemptive schedulers often configure a timer interrupt to fire when a process exceeds its time slice. This interrupt ensures that the scheduler will gain control to perform a context switch.
Interrupt handling[edit]
Modern architectures are interrupt driven. This means that if the CPU requests data from a disk, for example, it does not need to busy-wait until the read is over; it can issue the request (to the I/O device) and continue with some other task. When the read is over, the CPU can be interrupted (by a hardware in this case, which sends interrupt request to PIC) and presented with the read. For interrupts, a program called an interrupt handler is installed, and it is the interrupt handler that handles the interrupt from the disk.
When an interrupt occurs, the hardware automatically switches a part of the context (at least enough to allow the handler to return to the interrupted code). The handler may save additional context, depending on details of the particular hardware and software designs. Often only a minimal part of the context is changed in order to minimize the amount of time spent handling the interrupt. The kernel does not spawn or schedule a special process to handle interrupts, but instead the handler executes in the (often partial) context established at the beginning of interrupt handling. Once interrupt servicing is complete, the context in effect before the interrupt occurred is restored so that the interrupted process can resume execution in its proper state.
User and kernel mode switching[edit]
When the system transitions between user mode and kernel mode, a context switch is not necessary; a mode transition is not by itself a context switch. However, depending on the operating system, a context switch may also take place at this time.
Steps[edit]
In a switch, the state of the process currently executing must be saved somehow, so that when it is rescheduled, this state can be restored.
The process state includes all the registers that the process may be using, especially the program counter, plus any other operating system specific data that may be necessary. This is usually stored in a data structure called a process control block (PCB) or switchframe.
The PCB might be stored on a per-process stack in kernel memory (as opposed to the user-mode call stack), or there may be some specific operating system-defined data structure for this information. A handle to the PCB is added to a queue of processes that are ready to run, often called the ready queue.
Since the operating system has effectively suspended the execution of one process, it can then switch context by choosing a process from the ready queue and restoring its PCB. In doing so, the program counter from the PCB is loaded, and thus execution can continue in the chosen process. Process and thread priority can influence which process is chosen from the ready queue (i.e., it may be a priority queue).
Example[edit]
Considering a general arithmetic addition operation A = B+1. The instruction is stored in the instruction register and the program counter is incremented. A and B are read from memory and are stored in registers R1, R2 respectively. In this case, B+1 is calculated and written in R1 as the final answer. This operation as there are sequential reads and writes and there's no waits for function calls used, hence no context switch/wait takes place in this case.
However, certain special instructions require system calls that require context switch to wait/sleep processes. A system call handler is used for context switch to kernel mode. A display(data x) function may require data x from the Disk and a device driver in kernel mode, hence the display() function goes to sleep and waits on the READ operation to get the value of x from the disk, causing the program to wait and a wait for function call to tbe released setting the current statement to go to sleep and wait for the syscall to wake it up. To maintain concurrency however the program needs to re-execute the new value and the sleeping process together again.
Performance[edit]
Context switching itself has a cost in performance, due to running the task scheduler, TLB flushes, and indirectly due to sharing the CPU cache between multiple tasks.[4] Switching between threads of a single process can be faster than between two separate processes, because threads share the same virtual memory maps, so a TLB flush is not necessary.[5]
Hardware vs. software[edit]
Context switching can be performed primarily by software or hardware. Some processors, like the Intel 80386 and its successors,[6] have hardware support for context switches, by making use of a special data segment designated the task state segment (TSS). A task switch can be explicitly triggered with a CALL or JMP instruction targeted at a TSS descriptor in the global descriptor table. It can occur implicitly when an interrupt or exception is triggered if there's a task gate in the interrupt descriptor table (IDT). When a task switch occurs the CPU can automatically load the new state from the TSS.
As with other tasks performed in hardware, one would expect this to be rather fast; however, mainstream operating systems, including Windows and Linux,[7] do not use this feature. This is mainly due to two reasons:
- Hardware context switching does not save all the registers (only general-purpose registers, not floating point registers — although the
TSbit is automatically turned on in theCR0control register, resulting in a fault when executing floating-point instructions and giving the OS the opportunity to save and restore the floating-point state as needed). - Associated performance issues, e.g., software context switching can be selective and store only those registers that need storing, whereas hardware context switching stores nearly all registers whether they are required or not.
See also[edit]
References[edit]
- ^Tanenbaum, Andrew S.; Bos, Herbert (March 20, 2014). Modern Operating Systems (4th ed.). Pearson. ISBN978-0133591620.
- ^IA-64 Linux Kernel: Design and Implementation, 4.7 Switching Address Spaces
- ^Operating Systems, 5.6 The Context Switch, p. 118
- ^Chuanpeng Li; Chen Ding; Kai Shen. 'Quantifying The Cost of Context Switch'(PDF).Cite journal requires
|journal=(help) - ^Ulrich Drepper (9 October 2014). 'Memory part 3: Virtual Memory'. LWN.net.
- ^'Context Switch definition'. Linfo.org. Archived from the original on 2010-02-18. Retrieved 2013-09-08.
- ^Bovet, Daniel Pierre; Cesati, Marco (2006). Understanding the Linux Kernel, Third Edition. O'Reilly Media. p. 104. ISBN978-0-596-00565-8. Retrieved 2009-11-23.
External links[edit]
- Context Switching at OSDev.org
- Context Switch Definition by The Linux Information Project (LINFO)
- Context Switches from the Microsoft Developer Network (MSDN)
- General Architecture and Design -Interrupt Handling at FreeBSD.org
Contexts 3 6 1 – Fast Window Switcher Diagram System
