Note Update

content/Computer Organisation/Terminologies/Processor/GPU.md

@@ -11,7 +11,7 @@ References:
 ---
 ## Abstract
 ---
-- A [[Multi-core chips]] with thousands of tiny cores
+- A [[Multi-core Chip]] with thousands of tiny cores
 
 
 ## Benefits

content/DSA/Data Structure/Stack/Stack (FILO).md

@@ -21,7 +21,7 @@ References:
 
 
 >[!example] Use as
->1. Navigation in the [[Directory]] - the parent [[Directory]] is at the top of the stack
+>1. Navigation in the [[File System]] - the parent [[File System]] is at the top of the stack
 >2. Convert [[Recursion]] to be interactive
 
 >[!example] [Use Cases](https://github.com/youngyangyang04/leetcode-master#栈与队列

content/Linux/Directory/,etc,profile.d.md

@@ -9,6 +9,6 @@ Creation Date: 2023-09-09T16:51:05+08:00
 Last Date: 2023-09-09T16:51:05+08:00
 References:
 ---
->[!note] [[Directory]] ``/etc/profile.d``
+>[!note] [[File System]] ``/etc/profile.d``
 >-  Used for storing shell script files that are automatically sourced when a [[Linux/User|User]] logs into the system. 
 >- These scripts are used to set environment variables, customize the shell's behavior, and configure user-specific settings globally for all users.

content/Linux/Directory/,srv.md

@@ -9,7 +9,7 @@ Creation Date: 2023-08-10T00:28:36+08:00
 Last Date: 2023-08-10T00:28:36+08:00
 References:
 ---
->[!note] [[Directory]] ``/src``
+>[!note] [[File System]] ``/src``
 >- Typically used to store data that is served by the system
 >- The name "srv" stands for "service," 
 >- Often used to store data related to various services running on the system, such as websites, FTP servers, and other network services.

content/Linux/Terminologies/shebang.md

@@ -8,5 +8,5 @@ Creation Date: 2023-09-09T16:56:46+08:00
 Last Date: 2023-12-14T17:41:55+08:00
 References: 
 ---
-- ``#!`` used to specify the [[Pathname]] of the [[Interpreter]] of the program
+- ``#!`` used to specify the [[File System]] of the [[Interpreter]] of the program
 - A feature of [[Kernel]]

content/OS/MISC/Booting/Booting Computer.md

@@ -6,8 +6,8 @@ Author Profile:
 tags:
   - OS
 Creation Date: 2023-07-15T17:02:04+08:00
-Last Date: 2023-07-15T17:02:04+08:00
-References:
+Last Date: 2023-12-14T19:32:16+08:00
+References: 
 ---
 >[!note]
 >Booting sequence
@@ -21,6 +21,6 @@ References:
 >3. [[Secondary Boot loader]] started
 >4. [[OS]] started
 >	1. Get configuration info from BIOS
->	2. Check missing [[Device Driver]]
+>	2. Check missing [[Device Controller#Device Driver]]
 >	3. [[Initialize table]]
 >	4. Starts up a login program/GUI

content/OS/MISC/CPU/Asynchronous Single Threading.md

@@ -17,5 +17,5 @@ References:
 ## Cons
 ---
 ### No [[High-performance Computing#Parallelism (并行性)|Parallelism (并行性)]]
-- Only one single *thread*, thus can't take advantage of [[Multi-core chips]]
+- Only one single *thread*, thus can't take advantage of [[Multi-core Chip]]
 - Blocking the execution of the program when there is a *CPU Bounded* task

content/OS/MISC/CPU/Multi-Programming.md

@@ -20,5 +20,5 @@ References:
 
 ## Benefits
 ---
-### Full utilisation of [[Multi-core chips]]
+### Full utilisation of [[Multi-core Chip]]
 - More 

content/OS/MISC/CPU/Multi-core chips.md → content/OS/MISC/CPU/Multi-core Chip.md

@@ -5,13 +5,13 @@ Author Profile:
   - https://linkedin.com/in/xinyang-yu
 tags:
   - OS
-Creation Date: 2023-12-14T18:16:44+08:00
-Last Date: 2023-12-14T18:16:44+08:00
-References:
+Creation Date: 2023-11-11T19:03:44
+Last Date: 2023-12-14T18:51:41+08:00
+References: 
 ---
 ## Abstract
 ---
-- CPU with more than 1 core
+- With more than 1 [[CPU#Core]]
 - Need a [[Multi-processor OS]] to advantage of such chips
 
 ## Benefits

content/OS/MISC/CPU/Multi-processing.md

@@ -11,6 +11,6 @@ References:
 ---
 ## Abstract
 ---
-- Having multiple [[Process]] running at the same time on [[Multi-core chips]], offers true [[High-performance Computing#Parallelism (并行性)|Parallelism(并行性)]]
+- Having multiple [[Process]] running at the same time on [[Multi-core Chip]], offers true [[High-performance Computing#Parallelism (并行性)|Parallelism(并行性)]]
 - Can avoid issues like [[Deadlock (死锁)]] & [[Race Condition (竞态条件)]] faced by [[Multi-threading]] effectively but more resource heavy, because not sharing the same [[Address Space]], but independent [[Address Space]] comes with a cost 
 - Performance limited by the *number of CPU cores*

content/OS/MISC/CPU/Multitasking.md

@@ -6,33 +6,33 @@ Author Profile:
 tags:
   - OS
 Creation Date: 2023-09-24T12:23:00
-Last Date: 2023-12-14T18:16:44+08:00
+Last Date: 2023-12-14T19:42:42+08:00
 ---
 ## Abstract
 ---
 - Ability of computer executing multiple tasks at the same time by giving each [[Process]] a very small slice of [[CPU]] time
 - A logical extension of [[Multi-Programming]]
 - Focus on improving user experience 
-- Can be implemented on computers that have a single([[#Time-Sharing]]) or multiple [[CPU]]
-
-
-## Terminologies
----
-### Time-Sharing ([[High-performance Computing#Concurrency (并发)|Concurrency (并发)]])
-- A specific implementation of [[Multi-tasking]] when there is only a single resource - single [[CPU]], achieve with quick [[Context Switch]]
-- All Time-sharing systems are [[Multi-Programming]] systems
-- Allow multiple remote users to run jobs on the same computer at the same time 
+- Can be implemented on computers that have a single([[#Time-Sharing]]) or multiple CPU
 
+## 2 Approaches
 ### Corporative
-- Rather than [[OS]] decides when to preempt [[Process]]. [[Process]] gives up [[CPU]] and let other [[Process]] to run
-- [[Process]] can hog to [[CPU]] forever
-- Modern [[OS]] moves to [[#Preemptive Multitasking]]
+- Rather than [[OS]] decides when to preempt [[Process]]. Process gives up [[CPU]] and let other Process to run
+>[!caution] Process can hog to CPU forever, modern [[OS]] moves to [[#Preemptive Multitasking]]
 
 ### Preemptive Multitasking
 - Ensure no [[Process]] can hog the [[CPU]] forever
 #### Mechanism
-1. Before jumping to program code, the [[OS]] sets the [[Timer Chips]] to trigger an [[Interrupts (中断)]] after some period of time
+1. Before jumping to program code, the [[OS]] sets the [[Timer Chips]] to trigger an [[Interrupts (中断)#Hardware interrupts (外中断)]] after some period of time
 2. The OS switches to [[User Mode]] and jumps to the next [[Instruction]] of the program
-3. When the [[Timer Chips]] elapses, it triggers a [[Hardware interrupts (外中断)]] to switch to [[Kernel Mode]] and jump to OS code
-4. The OS can now save where the program left off, load a different program, and repeat the process.
->
+3. When the Timer Chips elapses, it triggers a Hardware interrupts (外中断) to switch to [[Kernel Mode]] and jump to OS code
+4. The OS can now save where the program left off, load a different program, and repeat the process
+
+## Terminologies
+---
+### Time-Sharing
+- A Implementation of [[High-performance Computing#Concurrency (并发)|Concurrency (并发)]]
+- A specific implementation of [[Multitasking]] when there is only a single resource - single [[CPU]], achieve with quick [[Context Switch]]
+- All Time-sharing systems are [[Multi-Programming]] systems
+- Allow multiple remote users to run jobs on the same computer at the same time 
+

content/OS/MISC/CPU/Privilege Level/Kernel Mode.md

@@ -6,9 +6,9 @@ Author Profile:
 tags:
   - OS
 Creation Date: 2023-10-07T16:38:28+08:00
-Last Date: 2023-10-07T16:38:28+08:00
-References:
+Last Date: 2023-12-14T19:32:09+08:00
+References: 
 ---
 >[!abstract] [[CPU]] is allowed to execute any supported [[Instruction]] and access any [[Main Memory]]
 
->[!note] [[Kernel]] & [[Device Driver]] run in kernel mode
+>[!note] [[Kernel]] & [[Device Controller#Device Driver]] run in kernel mode

content/OS/MISC/CPU/Privilege Level/User Mode.md

@@ -5,11 +5,11 @@ Author Profile:
   - https://linkedin.com/in/xinyang-yu
 tags:
   - OS
-Creation Date: 2023-12-14T18:16:44+08:00
-Last Date: 2023-12-14T18:16:44+08:00
-References:
+Creation Date: 2023-11-09T22:02:44
+Last Date: 2023-12-14T19:00:43+08:00
+References: 
 ---
 ## Abstract
 ---
-- Only a subset of [[Instruction]] is allowed, I/O and [[Main Memory]] access is limited, and many CPU settings are locked
-- Applications run in user mode
+- Only a subset of [[Instruction]] is allowed, I/O and [[Main Memory]] access are limited, and many [[CPU]] settings are locked
+- Applications run in this mode

content/OS/MISC/Types of OS/Multi-processor OS.md

@@ -9,7 +9,7 @@ Creation Date: 2023-11-13T19:06:12+08:00
 Last Date: 2023-11-13T19:06:12+08:00
 References:
 ---
-- Make use of multiple [[Computer Organisation/CPU/CPU]] and [[Multi-core chips]] in a single system
+- Make use of multiple [[Computer Organisation/CPU/CPU]] and [[Multi-core Chip]] in a single system
 
 > [!example]
 > - [[OS/MISC/UNIX vs Linux/Linux]]

content/OS/Main Components/Deadlock (死锁).md

@@ -0,0 +1,54 @@
+---
+Author:
+  - Xinyang YU
+Author Profile:
+  - https://linkedin.com/in/xinyang-yu
+tags:
+  - OS
+Creation Date: 2023-10-18T19:12:00
+Last Date: 2023-12-14T19:06:05+08:00
+References: 
+---
+## Abstract
+---
+- Waiting for something for *infinite time*, in which there is *no progress* for waiting [[Process]]
+- When all [[#Coffman conditions]] are fulfilled, it doesn't guarantee one, just prone to one
+- We have [[#Handling Strategies]] to handle deadlocks
+- Can only happen if there is *more than one lock*
+
+
+## Coffman conditions
+---
+- Useful for understanding and diagnosing [[Deadlock (死锁)]] situations
+- Provide a foundation for designing algorithms and systems that avoid deadlocks
+- 4 *necessary* conditions - [[#Mutual Exclusion]], [[#Hold and Wait]], [[#No Preemption]] & [[#Circular Wait]]
+### Mutual Exclusion
+- At least one resource must be held in a *non-shareable mode*.
+- This means that only *one* [[Process]] can use the resource at any given time
+- If another process requests the resource, that process must wait until the resource has been released
+
+### Hold and Wait
+- A process must be holding at least one resource and waiting to acquire additional resources that are currently being held by other processes
+
+### No Preemption
+- Resources cannot be [[Preemption]] from a process. They can only be released by the process holding them, typically after the process has finished its task.
+
+### Circular Wait
+- There exists a set of waiting processes such that P0 is waiting for a resource held by P1, P1 is waiting for a resource held by P2, and so on, with Pn waiting for a resource held by P0
+
+## Handling Strategies 
+---
+### Prevention
+- Ensure that at least one of the [[[Deadlock (死锁)#Coffman conditions]] does not hold. For example, by implementing a **resource allocation policy** that ensures no [[#Circular Wait]]
+- 
+- ### Avoidance 
+- The system has some additional a *prior information* available.
+- The most famous algorithm used for deadlock avoidance is the [[Banker's Algorithm]]
+
+### Detection
+- The system periodically checks for [[Deadlock (死锁)]]. If detected, actions are taken to recover from it
+
+### Ignorance
+- Simply ignore the problem and assume Deadlock (死锁) will never occur. 
+- This is suitable for some environments where deadlocks are rare and the overhead of other handling strategies is not justified
+

content/OS/Main Components/File System/File Descriptor.md

@@ -11,5 +11,5 @@ References:
 ---
 >[!note]
 >- A small integer
->- Returned when [[OS/Main Components/File System/File Types/File]] is accessible
+>- Returned when [[File System]] is accessible
 >- Used in subsequent operations