texonom/texonom-md · Datasets at Hugging Face

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dual booting	OS Mode	null	null	null	null	null	1. bitlocker locker 안끄고하면 encrypted 된다 - read linux partitoin - disk internals linux reader > [Paragon Software \| Main page](https://www.paragon-drivers.com/en/lfswin/#overview)	24656ee018014e6388b841b9f579c30c
System call	OS Mode	null	null	null	null	null	# fork() child return 0 parent returns child's pid # exec() make, new → has own main command(shell) executer # wait() to synchronize wait child pid ex. wait(&s) - s go to exit after wait → termination status(child) # exit() exit → exit status	f36194e943f3498593520460b36c55aa
Critical Section	Process Notion	Apr 21, 2021	Alan Jo	Alan Jo	Aug 10, 2023		상호배제, 진행, 한정된 대기를 충족	8469b236528b41efb4088ea3a69a4cc4
IPC	Process Notion	Nov 5, 2019	Alan Jo	Seong-lae Cho	Aug 10, 2023		inter process communication Done by kernel (client server model) # basic IPC pipe, named pipe(fifoi) # Advanced IPC massage pussing, semaphore(ipc facilities), shared mem = low levle socket (bsd) oriented ### # internet IPC socket api by packet ### udp - letter - criented ### tcp - phone call - connection oriented	98010a1077fd45968ce78ae98505b2e5
massage passing	Process Notion	Nov 5, 2019	Alan Jo	Seong-lae Cho	Aug 10, 2023			ab22575af94b441caad37d2e1697cd59
Monitor Sync	Process Notion	Nov 5, 2019	Alan Jo	Seong-lae Cho	Aug 10, 2023		Synchronize by using Mutex and Thread-safe Condition Variables(Queue) more simpler than Semaphore, because monitor Condition variable do lock and unlock. but Semaphore is done by in its process > 배타동기, 조건동기를 위한 큐가 각각 존재 > > ![](https://www.notion.so/image/https%3A%2F%2Fs3-us-west-2.amazonaws.com%2Fsecure.notion-static.com%2Fdb19c807-b616-411d-9a5a-1cececedaf6a%2Ftemp.jpg?table=block&id=07d2333c-4cc4-45d9-a778-ba9d66b14c42&cache=v2) > >	54b03a3282964bdb88207ec60dfeb1b2
Mutex	Process Notion	Nov 5, 2019	Alan Jo	Seong-lae Cho	Aug 10, 2023		mutex is type variable and has function lock and unlock lock(mutex), unlock(mutex)	cbfff707d2fe484ea20344f1104b7141
Process context	Process Notion	Nov 5, 2019	Alan Jo	Seong-lae Cho	Dec 3, 2022		- program context - kernel context	e76d70c66cd840b4a247de3310e85416
Process control block	Process Notion	Nov 5, 2019	Alan Jo	Seong-lae Cho	Dec 3, 2022		PCB - data registers - PC,SP registers - context	f62e2db348e442c580ea6d2084973973
Process descriptor	Process Notion	Nov 5, 2019	Alan Jo	Seong-lae Cho	Dec 3, 2022		PD - (p)ids, virtual memory structure	81614898a94d48058419b80e9e971fae
Process Exit	Process Notion	May 19, 2023	Alan Jo	Alan Jo	May 19, 2023		### Process Exit Code - 137 - Memory Issue - 127 - Command not found	2d82b561fba64541bde82c478297a22c
Process Function Call	Process Notion	Dec 3, 2022	Alan Jo	Alan Jo	Dec 3, 2022	[Process Memory](https://texonom.com/process-memory-53285d27582d49058052939d739e8623)	Process Function Call Management ### Process Function Call Notion \|Title\| \|:-:\| \|[Base Pointer](https://texonom.com/base-pointer-b2e339920fc947749be4e37d6ef87898)\| \|[Stack pointer](https://texonom.com/stack-pointer-3cba595dc071434eb2c9cf27dad65f57)\| \|[Activation Record](https://texonom.com/activation-record-9984197a3a144f878d427d71d6052a10)\| \|[Calling Sequence](https://texonom.com/calling-sequence-aeb9d35a8a714f048530391482503ccd)\|	ab41c2af3a5743599fca591ce08b535f
Process image	Process Notion	Nov 5, 2019	Alan Jo	Seong-lae Cho	Dec 3, 2022		- contains kernel space - code - low address - data - stack - heap - high address	c6384d00d1af41a6bcaa1b238165be17
Process Memory	Process Notion	Dec 3, 2022	Alan Jo	Alan Jo	Dec 3, 2022		### Process Memory Notion \|Title\| \|:-:\| \|[Stack Memory](https://texonom.com/stack-memory-70115a2851da415ca2aa913c7c5d3195)\| \|[Heap Memory](https://texonom.com/heap-memory-30304a87b33848bd97600adaaddbbfff)\| \|[Memory Model](https://texonom.com/memory-model-8d30211d5095420c82620b3b91be155f)\|	53285d27582d49058052939d739e8623
Process State	Process Notion	Nov 5, 2019	Alan Jo	Seong-lae Cho	Dec 3, 2022		### PSM(process state modeling) blocked queue > single blocked queue > multiple blocked queues (queue to event) > io bound system - CPU 에 물려있음 cpu bound system - io 에 물려있음	bbe0f9abe7b240c7a1d2a2d1c3478afd
Process switching	Process Notion	Nov 5, 2019	Alan Jo	Seong-lae Cho	Dec 3, 2022		→ mode(user) swithing - save process state only process swithing - save context(context switch), PCB(control block) → to appropriate queue update state of process → update mm structure	7f2486a6184241fba896860610a4d5f1
Process Sync	Process Notion	Nov 5, 2019	Alan Jo	Seong-lae Cho	Aug 10, 2023		smart person learn knowledge by network data structure but gard to use and administratenormal person learn knowldedge by tree data structure, so cannot imagine creative thinking which connect far distance in tree but close distance in network so i need to make network document site myself > critical section: where racing can be ocuurred ## issues Mutual Exclusion (상호배제): no two process execution in critical section Progress: no indefinite postpone while selection of process enter to critical section Bounded Waiting: no starvation # Solution ### 1. Locks - spinlocks - disabling inturrupts > for two-process case code ### Spinlock (software-only) 1. turn onlyping-pong like one-to-one problem 2. flag onlysymultaniously raising flag problem 3. Peterson's algorithmuse flag and turn variable > ```typerepeat flag[i] := true; turn := j; while (flag[j] and turn = j) //cation to and //busy waiting = spinning critical section flag[i] := false; //else code until false;``` ### spinlock (hardware atomic) by hardware support atomic operation > atomic operation: cannot be disturbed ### disabling interrupts prevent context switches acquire()/lock(): before critical sectionrelease()/unlock(): after critical section # Differences > ### Semaphore > Semaphore prevent multi-process access to data which are File type integer counter > Semaphore - unlock by other > supervise many resources > ![](https://www.notion.so/image/https%3A%2F%2Fs3-us-west-2.amazonaws.com%2Fsecure.notion-static.com%2Fde77dfc5-3c2a-4128-989c-7443486332d9%2Ftemp.jpg?table=block&id=71108d45-8e2a-4fe9-87dc-47519b809e9b&cache=v2) > > ### Mutex > Mutex(mutual exclusion) is object(variable) in process that prevent multi-thread access to data - use locking and unlocking > Mutex - self unlock > mutex is for two process - semaphore is for multi process use critical section > supervise only one resource > ![](https://www.notion.so/image/https%3A%2F%2Fs3-us-west-2.amazonaws.com%2Fsecure.notion-static.com%2F9ed7cd04-daba-4d0a-9a45-b75b72d1e370%2Ftemp.jpg?table=block&id=04dc4d93-4edb-40a4-bab1-868919034830&cache=v2) > All Mutex is Semaphore, Semaphore can be mutex, not all mutexes are Semaphore	45211a317f4f442cbab6b374fdaed630
Semaphore	Process Notion	Nov 5, 2019	Alan Jo	Seong-lae Cho	Aug 10, 2023		### Integer counter (File) variable S - cannot solve all dead lock - default value is resources number ### P function(try / decrement) - before critical section - wait(S) ### V function(increment) - after critical section -signal(S) two function should satisfy atomicity - other process cannot change while this function > 0 : block > ## Method 1 > ```typeP(S) { // do nothing - busy waiting while S <=0; S--; } V(S) { S++; }``` > ## Method 2 > ```typeP(S) { S--; if S < 0 // sleep this process } V(S) { S++; if S <= 0 // remove from sleep queue``` - semval : 세마포어의 값으로서 항상 양수가 지정된다. 여기에 값을 새로 지정하려면 반드시 세마포어 시스템 호출을 통해야하며 프로그램에서 일반 자료형의 변수와 같이 직접 접근 할 수는 없다. - sempid : 세마포어에 접근했던 최근의 프로세스의 프로세스 식별번호이다. - semncnt : 세마포어의 값이 현재보다 증가하기를 기다리는 프로세스의 갯수. - semzcnt : 세마포어의 값이 0으로 되기까지 기다리는 프로세스의 갯수 > >	46b11416972249d2a40e6c3e5060304a
Activation Record	Process Function Call Notion	Dec 3, 2022	Alan Jo	Alan Jo	Dec 3, 2022			9984197a3a144f878d427d71d6052a10
Base Pointer	Process Function Call Notion	Dec 3, 2022	Alan Jo	Alan Jo	Dec 3, 2022			b2e339920fc947749be4e37d6ef87898
Calling Sequence	Process Function Call Notion	Dec 3, 2022	Alan Jo	Alan Jo	Dec 3, 2022			aeb9d35a8a714f048530391482503ccd
Stack pointer	Process Function Call Notion	Dec 3, 2022	Alan Jo	Alan Jo	Dec 3, 2022			3cba595dc071434eb2c9cf27dad65f57
Heap Memory	Process Memory Notion	Oct 29, 2020	Alan Jo	Alan Jo	Dec 3, 2022		메모리 할당이 이루어지는 곳으로 선언한 변수와 함수들 동적 메모리 할당에 사용 포인터를 사용하여 데이터 위치를 저장 스택과 비교하여 데이터를 처리하고 접근하는 속도는 느리지만, 더 큰 용량의 데이터를 저장 컴파일타임에 메모리 사이즈를 정확히 예측할 수 없다 힙 메모리는 쓰레드간 공유 힙에 저장되는 데이터 종류로는 전역 변수 (global variables), 참조 타입(reference types) 할당된 힙 공간을 초과하는 메모리를 사용하려고 하면 OutOfMemory 에러가 발생 프로그램이 메모리를 더 이상 사용하지 않을 시에는 해당 메모리를 해제(free)해주어야 > [자바스크립트와 V8 엔진의 메모리 관리 프로세스](https://medium.com/naver-place-dev/%EC%9E%90%EB%B0%94%EC%8A%A4%ED%81%AC%EB%A6%BD%ED%8A%B8%EC%99%80-v8-%EC%97%94%EC%A7%84%EC%9D%98-%EB%A9%94%EB%AA%A8%EB%A6%AC-%EA%B4%80%EB%A6%AC-%ED%94%84%EB%A1%9C%EC%84%B8%EC%8A%A4-f45091e696e1)	30304a87b33848bd97600adaaddbbfff
Memory Model	Process Memory Notion	Dec 3, 2022	Alan Jo	Alan Jo	Dec 3, 2022			8d30211d5095420c82620b3b91be155f
Stack Memory	Process Memory Notion	Oct 29, 2020	Alan Jo	Alan Jo	Dec 3, 2022	[Process](https://texonom.com/process-ffd68f9e2b2648759b96047d48d17778)	### 프로그램의 어디에 있는지를 기록하는 자료 구조 콜스택의 각각은 스택프레임(Stack Frame) 데이터의 크기가 유한(finite)정적(static) 데이터의 크기가 컴파일타임에 계산 함수의 호출 정보 또한 스택 프레임으로 저장 각 프레임은 함수를 호출시 필요로하는 데이터를 저장한 한 블록의 공간을 의미 해당 함수가 새 변수를 생성하면, 그 데이터는 스택 맨 위의 블록에 저장 함수 호출이 종료되면 스택 맨 위 블록이 제거 멀티 스레딩이 가능한 어플리케이션은 스레드 수 만큼 스택을 여러개 일반적으로 스택에 저장되는 데이터 종류로는 지역변수(local variables), 포인터, 함수 프레임 스택에 저장될 수 있는 데이터의 사이즈에 상한이 있으며, 스택의 사이즈를 초과하는 경우에 StackOverflowError 가 발생 [Call Stack](https://texonom.com/call-stack-f041634136c74474bafad41496dff953) [Blowing the stack](https://texonom.com/blowing-the-stack-e20d822b114e4b17add6e5bff28e4a71) [Stack Trace](https://texonom.com/stack-trace-26fd9fe6f37242818d81284ff135c73d) > [자바스크립트와 V8 엔진의 메모리 관리 프로세스](https://medium.com/naver-place-dev/%EC%9E%90%EB%B0%94%EC%8A%A4%ED%81%AC%EB%A6%BD%ED%8A%B8%EC%99%80-v8-%EC%97%94%EC%A7%84%EC%9D%98-%EB%A9%94%EB%AA%A8%EB%A6%AC-%EA%B4%80%EB%A6%AC-%ED%94%84%EB%A1%9C%EC%84%B8%EC%8A%A4-f45091e696e1) [Heap Memory](https://texonom.com/heap-memory-30304a87b33848bd97600adaaddbbfff)	70115a2851da415ca2aa913c7c5d3195
Blowing the stack	Stack Memory	null	null	null	null	null	콜 스택의 최대 크기에 다다랐을 때	e20d822b114e4b17add6e5bff28e4a71
Call Stack	Stack Memory	null	null	null	null	null	실제 실행되는 코드를 순서대로 실행하는 곳	f041634136c74474bafad41496dff953
Stack Trace	Stack Memory	null	null	null	null	null	### 예외가 발생했을 때 콜스택의 상태	26fd9fe6f37242818d81284ff135c73d
`Device Queue`	Processor Queues	May 19, 2021	Alan Jo	Alan Jo	May 19, 2021		- I/O device의 처리를 기다리는 프로세스의 집합	453d40088668423c96d51003b27f9a2e
`Job Queue`	Processor Queues	May 19, 2021	Alan Jo	Alan Jo	May 19, 2021		- 현재 시스템 내에 있는 모든 프로세스의 집합	92bccac0db114b5c83a0f3ac0d9de17e
`Ready Queue`	Processor Queues	May 19, 2021	Alan Jo	Alan Jo	May 19, 2021		- 현재 메모리 내에 있으면서 CPU를 잡아서 실행되기를 기다리는 프로세스의 집합	c8546adf7d604a73a15b292808bef5b7
Processor Dispatcher	Processor Scheduler Notion	May 19, 2021	Alan Jo	Alan Jo	May 19, 2021		CPU 스케줄러 내부에 포함된 것 CPU의 제어권을 CPU Scheduler에 의해 선택된 프로세스에게 넘긴다 단기 스케줄러가 선택한 프로세스에 실질적으로 프로세서를 할당하는 역할 프로세스의 레지스터를 적재하고 Context Switching, Kernel Mode에서 User Mode로 전환시켜주며 프로세스가 다시 시작할 때 사용자 프로그램이 올바른 위치를 찾을 수 있도록 latency - to take dispatch overhead > [[O/S] CPU Scheduler와 Dispatcher](https://velog.io/@ss-won/OS-CPU-Scheduler%EC%99%80-Dispatcher)	dac6ca05f13c4ddc82906bd73f6080df
Long-term scheduler	Processor Schedulers	May 19, 2021	Alan Jo	Alan Jo	May 19, 2021		job scheduler	5f0783472fa94c478b10b7a1bfbf0192
Medium-term scheduler	Processor Schedulers	May 19, 2021	Alan Jo	Alan Jo	May 19, 2021		Swapper	15b70c90c2f641e696fcc6c90cbd04d9
Short-term scheduler	Processor Schedulers	May 19, 2021	Alan Jo	Alan Jo	May 19, 2021		CPU scheduler	f95f24cbd78d490c8a216dcabb04e4cb
CAS	Blocking	null	null	null	null	null	### compare-and-swap	b3541e0665b74cf7aa4f91a7b202fde2
Deadlock	Thread Notion	Nov 5, 2019	Alan Jo	Seong-lae Cho	Apr 3, 2023		# To-do - [ ] update last recovery part Deadlock problem - A set of blocked processes each holding a resource and waiting to acquire a resource held by another process in the set > - Has a set of processes > - Has a set of resources > - deadlocks can occur across machines (between I/O processes) > Paradigm of resource usage by process → > ![](https://www.notion.so/image/https%3A%2F%2Fs3-us-west-2.amazonaws.com%2Fsecure.notion-static.com%2Feb2997df-06f0-4a58-a3ab-8a260766ca4c%2FUntitled.png?table=block&id=b09cf27f-fd2c-4fde-ac6b-6e47c6f16cad&cache=v2) > ex. - semaphores A and B, initialized to 1 > - P1 and P2 each hold one tape drive and each needs another one > ![](https://www.notion.so/image/https%3A%2F%2Fs3-us-west-2.amazonaws.com%2Fsecure.notion-static.com%2F295577a4-2317-41fe-a9f6-1189a2a6234b%2FUntitled.png?table=block&id=2c8323b5-ea0d-4f36-afe3-5e629c1ac5a5&cache=v2) > Deadlock problem is important in special purpose OS # Bridge Crossing > - it can be resolved if one car backs up - preempt resources and rollback > - Several cars may have to be backed up(kill process) if a deadlock occurs > - Starvation is possible > ![](https://www.notion.so/image/https%3A%2F%2Fs3-us-west-2.amazonaws.com%2Fsecure.notion-static.com%2Fb18b9b81-b9ab-4d66-b14c-c7d635c684c2%2FUntitled.png?table=block&id=a0e07da0-3140-4acf-9739-fcbee231f253&cache=v2) > Kill process need restart process - Why? # Resource Allocation Graph > $$G = (V, E).$$ > Model tuple of the state of a computer system as a directed graph > Request edge : process to resource (not to special one resource set itself) > Allocation edge : resource to process > > ![](https://www.notion.so/image/https%3A%2F%2Fs3-us-west-2.amazonaws.com%2Fsecure.notion-static.com%2F0b47c6e3-caf9-44ec-822a-2bb25517d3e1%2FUntitled.png?table=block&id=bb437e11-4e02-4313-a5e3-a4af541a760e&cache=v2) > ## Theorem 1 > If a graph does not contain a cycle then no processes are deadlocked > ## Theorem 2 > If there is only a “single” instance per resource type, then a set of processes are deadlocked if and only if the processes and resources form a cycle in the resource allocation graph ## “Necessary” Conditions for a Deadlock Deadlock can arise if the following four conditions hold simultaneously - at the same time 1. Mutual exclusion : only one process at a timfe can use a resource. 2. Hold and wait : a process holding at least one resource is waiting to acquire additional resources held by other processes. 3. No preemption : a resource can be released only voluntarily by the process holding it. 4. Circular wait : a cycle in the resource allocation graph ### So we will not make this conditions simultaneously by Handling Deadlocks > theorem 2 is only enable sufficient condition ## Method 1: Deadlock Prevention Ensure that one of the four deadlock conditions never occur ← make one false among 4 (not about information, policy and data structure change) <details><summary> 1 → make shareable share</summary> make mutual exclusive available resources to not exclusively is impossible → Must hold for non-shareable resources </details> <details><summary> 2 → No wait or No hold (resources utilization become low, starvation possible)</summary> Guarantee that whenever a process requests a resource, it does not hold any other resources Require process to request and be allocated “all” its resources before it begins execution, or allow process to request resources only when the process has “none”. </details> <details><summary> 3 → become preemptive (stop while processing)</summary> If a process that is holding some resources requests another resource that cannot be immediately allocated to it, then all resources currently being held are released Preempted resources are added to the list of available resources Process will be restarted only when it can regain its old resources, as well as the new ones that it is requesting Can be applied to resources whose state can be easily saved and restored later : e.g. CPU registers, memory, … </details> <details><summary> 4 → remove cycle (if no resources can be substituted → Theorem 2) most used method</summary> Impose a total ordering of all resource types, and require that each process requests resources in order of enumeration </details> ## Method 2: Deadlock Avoidance Avoid deadlock by run-time checking and allocation of resources - check before allocate (never enter an unsafe state) <details><summary> Requires that the system has some additional a priori information and algorithm</summary> Simplest and most useful model requires that each process declare the maximum number of resources of each type that it may need The deadlock-avoidance algorithm dynamically examines the “resource-allocation state” to ensure that there can never be a circular-wait condition </details> - Safe State : System is in safe state if there exists a safe sequence of all processes requests resource → decide immediate allocation leaves the system in a “safe” state > Resource-allocation state is defined by the number of available and allocated resources, and the maximum demands of the processes ### Then How can we do that by what algorithm? if resource is single instance → use resource allocation graph and check cycle > if resource is multiple instance → > > [Banker's algorithm](https://texonom.com/bankers-algorithm-a3e9530ac45b4c61806354379b55c593) > ## Method 3: Deadlock Detection and Recovery Let the system deadlock and then deal with it (No a priori information, algorithm exist) ### Detection Algorithm Request: an n x m matrix indicates the current request of each process (Replace Need with Request matrix) - it is safety algorithm in banker's algorithm > usually each process is not assumed to have knowledge in its maximum use Then how often we will invoke algorithm - have no answer ## Recovery from Deadlock <details><summary> Methods of recovery</summary> </details> 5. Process terminate - lose all process, not easy to recover process done 6. resource preemption > - Selecting a victim, rollback, starvation is an issue > ![](https://www.notion.so/image/https%3A%2F%2Fs3-us-west-2.amazonaws.com%2Fsecure.notion-static.com%2F7bc1d018-01cc-425b-a17c-ec7615a6adb2%2FUntitled.png?table=block&id=60291423-d42a-4d02-a3e5-ed94f7618e42&cache=v2) > if resource is multiple instance → Detection algorithm like banker's algorithm > caution of starvation → aging > need to kill cause process → re-deadlock > Rollback - 최소한 싸이클이 없어질 만큼의 프로세스는 죽여야 한다. > wait for 그래프는 어떤 프로세스가 어떤 리소스를 wait하고 있는가만 체크한다. 싸이클이 발생했으면 데드락이 발생 한 것이다. > if resource is single instance → check wait-for graph 주깆거 ### Method 4: No policy Ignore the problem and pretend that deadlocks never occur in the system → just reboot Used by most operating systems, including UNIX and Windows ← too much overhead # Reference - Refer Lock hierarchy > [DeadLock](https://ozt88.tistory.com/35)	8c118f296cc1477aac5c59c75cec8235
kernel level thead	Thread Notion	Nov 5, 2019	Alan Jo	Seong-lae Cho	May 11, 2021			498f95b4e748492b8e2ed535bf987b0b
Lock convoy	Thread Notion	Nov 5, 2019	Alan Jo	Seong-lae Cho	May 11, 2021		Lock을 소유하길 기다리는 비율이 Lock을 해제하는 비율보다 높은 것 Lock Convoy가 발생하게 되면 시스템의 성능이 급격하게 떨어지게	a904af475dcb4bb8a0d99ea8e095de39
Priority Inversion	Thread Notion	Mar 28, 2021	Alan Jo	Alan Jo	May 11, 2021		윈도우 운영체제에서 Thread에는 항상 우선순위라는 것이 있고, 윈도우 운영체제는 항상 우선순위가 높은 Thread만 실행시키는 스케줄링 정책을 사용 여러개의 우선순위가 lock 과 엮어서 발생하는 성능저하	beb6115d6154481db836a5677f877581
Thread Safe	Thread Notion	May 11, 2021	Alan Jo	Alan Jo	May 11, 2021			a6b8ab6ec6e146deafa86b428e5ecfbe
Threads model	Thread Notion	Mar 28, 2021	Alan Jo	Alan Jo	May 11, 2021		- one to one - n to n	800491618af24626b02f701d43578b66
Threads Scheduling	Thread Notion	Nov 5, 2019	Alan Jo	Seong-lae Cho	May 11, 2021		Local Scheduling Global Scheduling	e1315fdaa06740c6ab54f097edeba1d7
Two-Step Dance	Thread Notion	Mar 28, 2021	Alan Jo	Alan Jo	May 11, 2021		불필요한 Context Switch를 발생	b328c6d4bef8483a97e076bbc91b0be8
Banker's algorithm	Deadlock	null	null	null	null	null	### It is Deadlock Avoidance itself Define a set of vectors and matrices that characterize the current state of all resources and processes > Each process must a priori claim maximum use # DataStructure - n - process number, m resource type number. - Available : one dimension array of length m - store available resources number by resource type - Max (require to retire process): two dimension array of m x n - process i require j type and express it by max[i,j] - Allocation : two dimension array of m x n - how much allocated - allocation[i,j] - Need : two dimension array of m x n - (Need = Max - Allocation) how much more need ### Banker's algorithm is function of input Request Request_i : one dimension array of length m - request vector for process Pi ![](https://www.notion.so/image/https%3A%2F%2Fs3-us-west-2.amazonaws.com%2Fsecure.notion-static.com%2F7b38698d-432a-474a-bdde-51b3874c093e%2FUntitled.png?table=block&id=48f55dad-e108-4519-8bff-2aea677cb0f5&cache=v2) # Safety Algorithm Work(copy of Available) and Finish(initialized false for all process) be vectors of length m and n, respectively → fine sequence of execution ### Result is no → process must wait ## Difference All tow algorithm is Deterministic Algorithm but Banker's is determine for Allocation Detection is determine of checking deadlock - Banker's Algorithm is virtual verification of unassigned resource by simulation - Detection Algorithm is check stage is safe or not	a3e9530ac45b4c61806354379b55c593
user level thread	Thread Types	Nov 5, 2019	Alan Jo	Seong-lae Cho	May 11, 2021			6f68e5d2dff240359b9b494534598b29
Processor Scheduling Algorithm	Processor Scheduling Usages	May 19, 2021	Alan Jo	Alan Jo	Feb 21, 2023		### Processor Scheduling Algorithms \|Title\| \|:-:\| \|[FCFS](https://texonom.com/fcfs-edf5b1ac74e8471fa9e35f31239295ba)\| \|[SJF](https://texonom.com/sjf-0cf78004bc7848a69e2f1aa607a20e02)\| \|[Round Robin](https://texonom.com/round-robin-45c43acd37de47f88881d01d9e3eb925)\| \|[Multilevel Queue](https://texonom.com/multilevel-queue-123add4d32274321a8643d4e927b52cc)\| \|[Multilevel Feedback Queue](https://texonom.com/multilevel-feedback-queue-ee4381e712ad4f869e3523655e84bd16)\|	305e26d3aca84cdd9e5c980e91642a8f
Processor Scheduling Evaluation	Processor Scheduling Usages	May 19, 2021	Alan Jo	Alan Jo	Feb 21, 2023		Queueing Model Implementation & Measurement Simulation > [[OS] 5-2. CPU Scheduling II](https://asfirstalways.tistory.com/124)	b897d00ffba948e6922c062d95693455
Processor Scheduling Method	Processor Scheduling Usages	May 19, 2021	Alan Jo	Alan Jo	Feb 21, 2023		### Processor Scheduling Methods \|Title\| \|:-:\| \|[Multi Processor Scheduling](https://texonom.com/multi-processor-scheduling-7e3b60b954004bb098a7c70ee46677ad)\| \|[Homogeneous Processor Scheduling](https://texonom.com/homogeneous-processor-scheduling-b643b19e38da4a5a920fd860364fa082)\| \|[Load Sharing](https://texonom.com/load-sharing-6bb863d9c38f4e628781db57c1345107)\| \|[Symmetric Multi Processor](https://texonom.com/symmetric-multi-processor-b3d5801f4b80479bb71fdb7f737d0255)\| \|[Asymmetric Multi Processor](https://texonom.com/asymmetric-multi-processor-0e36cbc355d54549887b513bfb752d8d)\| \|[Real time Sharing](https://texonom.com/real-time-sharing-2a9baa85c15947b5a8032f20a51590d1)\|	c5c243a128b74b2183508330aec1090c
FCFS	Processor Scheduling Algorithms	Mar 28, 2021	null	null	null		[Convoy Effect](https://texonom.com/convoy-effect-bb94c5b2e41647328547674819b2d5db)	edf5b1ac74e8471fa9e35f31239295ba
Multilevel Feedback Queue	Processor Scheduling Algorithms	Mar 28, 2021	null	null	null			ee4381e712ad4f869e3523655e84bd16
Multilevel Queue	Processor Scheduling Algorithms	Mar 28, 2021	null	null	null			123add4d32274321a8643d4e927b52cc
Round Robin	Processor Scheduling Algorithms	Mar 28, 2021	null	null	null		꽤 현대적인 방식 동일한 크기의 할당시간 time quantum의 tradeoff를 잘해야	45c43acd37de47f88881d01d9e3eb925
SJF	Processor Scheduling Algorithms	Mar 28, 2021	null	null	null		Starvation 발생	0cf78004bc7848a69e2f1aa607a20e02
Convoy Effect	FCFS	null	null	null	null	null	소요시간 긴 프로세스가 먼저 시간 다 소모	bb94c5b2e41647328547674819b2d5db
Asymmetric Multi Processor	Processor Scheduling Methods	Mar 28, 2021	null	null	null			0e36cbc355d54549887b513bfb752d8d
Homogeneous Processor Scheduling	Processor Scheduling Methods	Mar 28, 2021	null	null	null			b643b19e38da4a5a920fd860364fa082
Load Sharing	Processor Scheduling Methods	Mar 28, 2021	null	null	null			6bb863d9c38f4e628781db57c1345107
Multi Processor Scheduling	Processor Scheduling Methods	Mar 28, 2021	null	null	null			7e3b60b954004bb098a7c70ee46677ad
Real time Sharing	Processor Scheduling Methods	Mar 28, 2021	null	null	null		[hard real time system](https://texonom.com/hard-real-time-system-addff3ce5ba24ef2bd993d0e016f6db7) [soft real time system](https://texonom.com/soft-real-time-system-c653ddd54a304bc0badef7aa5b33782d)	2a9baa85c15947b5a8032f20a51590d1
Symmetric Multi Processor	Processor Scheduling Methods	Mar 28, 2021	null	null	null			b3d5801f4b80479bb71fdb7f737d0255
hard real time system	Real time Sharing	null	null	null	null	null		addff3ce5ba24ef2bd993d0e016f6db7
soft real time system	Real time Sharing	null	null	null	null	null		c653ddd54a304bc0badef7aa5b33782d
Punch Card	OS History	null	null	null	null	null	- 포트란은 초기에 펀치카드로 작성하였기 때문에 FORTRAN 77 까지만 해도 프로그램을 작성할 때 앞에 6 컬럼을 띄우지 않으면 오류가 발생 - 펀치카드는 80 컬럼을 가지고 있는데 이것은 요즘에도 코드작성 규칙에 사용 - 펀치카드는 프로그램 순서대로 정리되어 있는 것이기 때문에 만약에 들고 가다가 떨어뜨리기라도 하면 다시 순서대로 정리해야 했음 > [Introduction](https://mug896.github.io/bash-shell/tty.html)	dcb71893cc074afb9ec6865b43eaaa61
GUI	OS Components	Sep 27, 2020	Alan Jo	Alan Jo	Apr 3, 2023	[CLI](https://texonom.com/cli-3b46069e77904f7b8ce85faff6252cfc)	## Graphic System ### Graphic System Notion \|Title\| \|:-:\| \|[Window System](https://texonom.com/window-system-2c3d5baf4f1647548307c2eead61d093)\| \|[GUI Toolkit](https://texonom.com/gui-toolkit-cbc5815c18b743ea9c94df528097ff47)\| > [Graphical User Interface Gallery](http://toastytech.com/guis/index.html) > [1. 리눅스 그래픽 시스템과 Wayland/Weston](https://prographics.tistory.com/2)	936270e7b4af43e3929f69fcb6e1e2e4
GUI Toolkit	Graphic System Notion	Dec 28, 2021	Alan Jo	Alan Jo	Mar 13, 2023		### GUI Toolkits \|Title\| \|:-:\| \|[GTK](https://texonom.com/gtk-eea634600ab54d4580c59a29261e1189)\| \|[QT](https://texonom.com/qt-b9dda98c59cb4af792ca1603406e4fc8)\|	cbc5815c18b743ea9c94df528097ff47
Window System	Graphic System Notion	Sep 27, 2020	Alan Jo	Alan Jo	Apr 28, 2023		### Window System Notion \|Title\| \|:-:\| \|[Display Server](https://texonom.com/display-server-01e7cd4e7a35425abebbe16c50e5b93f)\| \|[Desktop Environment](https://texonom.com/desktop-environment-7a1bd7322f614338b3905a3370bf4d2f)\| \|[Window Manager](https://texonom.com/window-manager-7f27fac502ea4471b9f9c377e49ec11e)\| \|[Window System History](https://texonom.com/window-system-history-84f6c1586f1d49de855d5f315176e030)\| \|[Window Controls Overlay](https://texonom.com/window-controls-overlay-e947399311d94fe59a014856df820f2f)\| ![](https://www.notion.so/image/https%3A%2F%2Fs3-us-west-2.amazonaws.com%2Fsecure.notion-static.com%2F56f6bcd2-61a0-4089-a8ab-9d207ea27c1c%2FUntitled.png?table=block&id=e698214d-9003-465d-aff6-8043d356b8b3&cache=v2) 위와같이 구성된 커널이상을 총제적으로 부르는 말 또는 Windows, Mac과같이 구성이 감춰진 ### Window Systems \|Title\| \|:-:\| \|[X window System](https://texonom.com/x-window-system-b037d52fa7fe4d33a21b16299817b92e)\| \|[Desktop Window Manager](https://texonom.com/desktop-window-manager-efa76bde65954247a6a40caa469807e5)\| > [1. 리눅스 그래픽 시스템과 Wayland/Weston](https://prographics.tistory.com/2) > [Windowing system - Wikipedia](https://en.wikipedia.org/wiki/Windowing_system#Display_server_communications_protocols)	2c3d5baf4f1647548307c2eead61d093
GTK	GUI Toolkits	Dec 28, 2021	Alan Jo	Alan Jo	Mar 13, 2023		## Gimp ToolKit GNU Image Manipulation Program	eea634600ab54d4580c59a29261e1189
QT	GUI Toolkits	Dec 28, 2021	Alan Jo	Alan Jo	Mar 13, 2023		상업사용은 유료	b9dda98c59cb4af792ca1603406e4fc8
Desktop Environment	Window System Notion	Dec 28, 2021	Alan Jo	Alan Jo	Apr 28, 2023		## Graphic Interface ### Toolkit based ### QT Desktop Environment \|Title\| \|:-:\| \|[KDE Plasma](https://texonom.com/kde-plasma-dfcb7fc088e746a7b1114b85ea230469)\| \|[Deepin](https://texonom.com/deepin-77cccfda81604e54aabf2e266f18d406)\| \|[lxqt](https://texonom.com/lxqt-2f255f136b124c38b927b8b706f1a707)\| \|[Maui Shell](https://texonom.com/maui-shell-e38cb7e552b448d484c8a6909fa88b8c)\| ### GTK Window Systems \|Title\| \|:-:\| \|[GNOME](https://texonom.com/gnome-f4f9012077c34e4dbc6357f5521ed9f2)\| \|[mate](https://texonom.com/mate-e91f7ecd17d64cd2a02f82c26b5f97b1)\| \|[xfce](https://texonom.com/xfce-c4015594465948aca9785d97550774ae)\| \|[lxde](https://texonom.com/lxde-39d1343c6bc44acc983c99ba2c6377fb)\| \|[Cinammon](https://texonom.com/cinammon-cea163f87afa4d6e8b1b1867a8112921)\|	7a1bd7322f614338b3905a3370bf4d2f
Display Server	Window System Notion	Dec 28, 2021	Alan Jo	Alan Jo	Apr 28, 2023		## Window Compositor 각각의 윈도우 화면을 갱신하고, 겹쳐진 윈도우들을 하나의 화면으로 보여주는 기능 ### Display Servers \|Title\| \|:-:\| \|[Wenston](https://texonom.com/wenston-8c38ac264bec41f59eb1104934a18768)\| \|[Xorg Server](https://texonom.com/xorg-server-4198e168f18347f4ad7b933f4b54a051)\| \|[Quartz Compositor](https://texonom.com/quartz-compositor-fcbf4e0f615a4139b05f25c7b607b815)\| \|[SurfaceFlinger](https://texonom.com/surfaceflinger-a40de1645ce543f3845dcfeadc7c4f4d)\| ### Display Server Protocols \|Title\| \|:-:\| \|[Wayland](https://texonom.com/wayland-670af55e623a4d879e43f34ecc7b0af1)\| \|[Quartz ](https://texonom.com/quartz-5871fb969408471e833d098f00f82cf4)\| \|[X11](https://texonom.com/x11-5f4c77af06d04862a8b42353a3dc81fc)\| > [Compositing window manager - Wikipedia](https://en.wikipedia.org/wiki/Compositing_window_manager)	01e7cd4e7a35425abebbe16c50e5b93f
Window Controls Overlay	Window System Notion	Jun 14, 2022	Alan Jo	Alan Jo	Apr 28, 2023		electron에서도 지원 > [Window Controls Overlay](https://wicg.github.io/window-controls-overlay/)	e947399311d94fe59a014856df820f2f
Window Manager	Window System Notion	Dec 28, 2021	Alan Jo	Alan Jo	Apr 28, 2023		- tiling method > - awesome - dynamic method > - i3 > - bspwm > [Desktop Window Manager - Wikipedia](https://en.wikipedia.org/wiki/Desktop_Window_Manager) > [Window manager - Wikipedia](https://en.wikipedia.org/wiki/Window_manager)	7f27fac502ea4471b9f9c377e49ec11e
Window System History	Window System Notion	Mar 18, 2021	Alan Jo	Alan Jo	Apr 28, 2023		![](https://www.notion.so/image/https%3A%2F%2Fs3-us-west-2.amazonaws.com%2Fsecure.notion-static.com%2F9572d36b-e062-45f3-a829-3d877c5dc8c3%2FUntitled.png?table=block&id=066ac973-63ce-408c-93fb-542ab4220051&cache=v2) ![](https://www.notion.so/image/https%3A%2F%2Fs3-us-west-2.amazonaws.com%2Fsecure.notion-static.com%2F6d8217b2-889a-4796-92ad-d054c0ee2f17%2FUntitled.png?table=block&id=02fde864-c238-40c8-9f08-67d0b31721c5&cache=v2) > [1. 리눅스 그래픽 시스템과 Wayland/Weston](https://prographics.tistory.com/2)	84f6c1586f1d49de855d5f315176e030
Cinammon	GTK Window Systems	Feb 3, 2020	null	null	null	null	gnome3 based	cea163f87afa4d6e8b1b1867a8112921
GNOME	GTK Window Systems	Jan 20, 2020	null	null	null	null	[gnome2](https://texonom.com/gnome2-de3408eafdf543708f272b99eabb0df9) [gnome3](https://texonom.com/gnome3-a3a97de6938d406786ec9f6fa0d8534f) [gnome 40](https://texonom.com/gnome-40-71eca2986dc942bdacad3ab797582e43) [gtk](https://texonom.com/gtk-5b7dfb6bb3644ba1bc24062fd5bb6bf6) - dark theme ```typeecho 'gtk-application-prefer-dark-theme=1' >> ~/.config/gtk-3.0/settings.ini``` > [How to change "Global Dark Theme" on and off through Terminal?](https://askubuntu.com/questions/769417/how-to-change-global-dark-theme-on-and-off-through-terminal) - shutdown dialogue box ```typegnome-session-quit --power-off```	f4f9012077c34e4dbc6357f5521ed9f2
lxde	GTK Window Systems	Dec 28, 2021	null	null	null	null		39d1343c6bc44acc983c99ba2c6377fb
mate	GTK Window Systems	Dec 28, 2021	null	null	null	null		e91f7ecd17d64cd2a02f82c26b5f97b1
xfce	GTK Window Systems	Dec 28, 2021	null	null	null	null		c4015594465948aca9785d97550774ae
gnome 40	GNOME	null	null	null	null	null	> [GNOME 40](https://forty.gnome.org/)	71eca2986dc942bdacad3ab797582e43
gnome2	GNOME	null	null	null	null	null		de3408eafdf543708f272b99eabb0df9
gnome3	GNOME	null	null	null	null	null		a3a97de6938d406786ec9f6fa0d8534f
gtk	GNOME	null	null	null	null	null		5b7dfb6bb3644ba1bc24062fd5bb6bf6
Deepin	QT Desktop Environment	Jan 21, 2020	null	null	null	null	> [팁 & 테크 - 리눅스 대초보자의 Deepin OS 사용 후기 공유합니다.](https://hamonikr.org/board_bFBk25/47852)	77cccfda81604e54aabf2e266f18d406
KDE Plasma	QT Desktop Environment	Jan 20, 2020	null	null	null	null	### KDE Plasma Notion \|Title\| \|:-:\| \|[Konqueror](https://texonom.com/konqueror-0476051dcfbd4b15ba20cb96dbd09ace)\| dolphin - explorer, terminal - 전역 테마 - dark breeze - 프로그램 모양 - 창장식 - breezemite dark - icon - qogir dark kde ui framework - kirigami ### kde on windows > [Windows - KDE Community Wiki](https://community.kde.org/Windows) ### linux mint > [How to Install KDE Desktop Environment on Linux Mint 19 Tara](https://linuxhint.com/install_kde_linux_mint_19/)	dfcb7fc088e746a7b1114b85ea230469
lxqt	QT Desktop Environment	Dec 28, 2021	null	null	null	null		2f255f136b124c38b927b8b706f1a707
Maui Shell	QT Desktop Environment	Dec 28, 2021	null	null	null	null	[Cask](https://texonom.com/cask-cf0a491a64bf4fad80de279d5000f3af) [Zpace](https://texonom.com/zpace-9bd7338a34964f8d8e0ce3227be07714) [maui-shell](https://github.com/Nitrux/maui-shell)	e38cb7e552b448d484c8a6909fa88b8c
Konqueror	KDE Plasma Notion	Jun 20, 2020	Alan Jo	Alan Jo	Dec 28, 2021		> [Untitled](https://namu.wiki/w/KDE?from=KHTML)	0476051dcfbd4b15ba20cb96dbd09ace
Cask	Maui Shell	null	null	null	null	null	shell container and elements templates, such as panels, popups, cards etc	cf0a491a64bf4fad80de279d5000f3af
Zpace	Maui Shell	null	null	null	null	null	composer, which is the layout and places the windows or surfaces into the Cask container	9bd7338a34964f8d8e0ce3227be07714
Quartz	Display Server Protocols	Dec 28, 2021	Alan Jo	Alan Jo	Apr 28, 2023			5871fb969408471e833d098f00f82cf4
Wayland	Display Server Protocols	Sep 27, 2020	Alan Jo	Alan Jo	Apr 28, 2023	[Wenston](https://texonom.com/wenston-8c38ac264bec41f59eb1104934a18768)	오픈소스 컴포지터중 가장 유명 ### Wayland Notion \|Title\| \|:-:\| \|[wayland Hisotory](https://texonom.com/wayland-hisotory-b10ae19c8caa4cd398729d129a823db9)\| \|[Wayland IVI Extension](https://texonom.com/wayland-ivi-extension-ab8337e4cd80457a9ac7d3d3f466b620)\| \|[ivi-shell](https://texonom.com/ivi-shell-a6873868b110490fbd30a0dedbe7d07c)\| \|[Wayland Surface](https://texonom.com/wayland-surface-28be7b2823fc4daf9fa6db800f10874a)\| ### opengl, Mesa, DRM에 대한 개념 없이 wayland의 구현을 이해할 수는 없다 wayland는 초창기에 Kristian Høgsberg에 의해 기존 X window를 더 단순하고 모던하게 바꾸려는 목적과 함께 오픈소스 프로젝트로서 주도 wayland 레퍼런스 컴포지터인 weston의 개발이 함께 시작 개발 시작의 이유는 X window에서 수행되던 수많은 하부 기능들이 커널(memory management, command scheduling, mode setting)이나 라이브러리(cairo, pixman, freetype, fontconfig, pango, etc)로 옮겨져 사용 되지 않음에도 불구하고 user는 잔존해 있는 X protocol을 지원해야만 했기 때문 그래픽 카드 하드웨어를 응용 프로그램이 직접 제어할 수 있게 하는 것이 특징 ![](https://www.notion.so/image/https%3A%2F%2Fs3-us-west-2.amazonaws.com%2Fsecure.notion-static.com%2Fddaadde5-a418-43cb-830c-cc830aeeb3ee%2FUntitled.png?table=block&id=2b8a0b8d-370b-4f10-8ee1-cd0751dd776c&cache=v2) wayland를 사용하는 대표적인 이유 - 기존 대비(X11) 경량화, 체계화 된 프레임웍 - 기존의 X11이 사용하지 않는 부분을 제거하고 필요한 부분 만을 구현 - 표준 GEM/DRM 스택을 이용하여 최대한 단순하게 구현(커널에서 DRM/GEM을 지원하여 더 이상 user framework이 복잡해 질 필요가 없음) - Genivi, AGL, Tizen 플랫폼에서 사용 - X11의 1/10크기 > [1. 리눅스 그래픽 시스템과 Wayland/Weston](https://prographics.tistory.com/2)	670af55e623a4d879e43f34ecc7b0af1
X11	Display Server Protocols	Dec 28, 2021	Alan Jo	Alan Jo	Apr 28, 2023			5f4c77af06d04862a8b42353a3dc81fc
ivi-shell	Wayland Notion	Sep 27, 2020	Alan Jo	Alan Jo	Mar 13, 2023		wayland의 서페이스(wl_surface)를 ivi-application 프로토콜에 맵핑하여 surface, layer, screen의 관리 기능을 지원하는 plugin	a6873868b110490fbd30a0dedbe7d07c
wayland Hisotory	Wayland Notion	Mar 18, 2021	Alan Jo	Alan Jo	Mar 13, 2023		[X.Org](http://x.org/) 재단 개발자 몇 명이 만든 X 윈도 서비스를 대체하기 위한 디스플레이 서버	b10ae19c8caa4cd398729d129a823db9
Wayland IVI Extension	Wayland Notion	Sep 27, 2020	Alan Jo	Alan Jo	Mar 13, 2023			ab8337e4cd80457a9ac7d3d3f466b620
Wayland Surface	Wayland Notion	Sep 27, 2020	Alan Jo	Alan Jo	Mar 13, 2023			28be7b2823fc4daf9fa6db800f10874a
Quartz Compositor	Display Servers	Mar 18, 2021	Alan Jo	Alan Jo	Apr 28, 2023		OS X이 사용하는 윈도 시스템 > [What is the architecture of Mac OS X's windowing system?](https://unix.stackexchange.com/questions/517/what-is-the-architecture-of-mac-os-xs-windowing-system)	fcbf4e0f615a4139b05f25c7b607b815
SurfaceFlinger	Display Servers	Mar 18, 2021	Alan Jo	Alan Jo	Apr 28, 2023		안드로이드	a40de1645ce543f3845dcfeadc7c4f4d
Wenston	Display Servers	Sep 27, 2020	Alan Jo	Alan Jo	Apr 28, 2023	[Wayland](https://texonom.com/wayland-670af55e623a4d879e43f34ecc7b0af1)	### Implement Wayland protocol/compositor - Shell plugin 지원(desktop-shell, xdg-shell …) - weston은 윈도우들을 여러 계층으로(레이어) 구분해서 관리한다(마우스 커서 뷰, app1 뷰, app2 뷰 …) - weston은 shell을 이용하여 출력되는 각 윈도우(뷰)의 순서를 결정한다 - weston은 윈도우를 화면에 나타나게 하거나 위치를 옮기거나 크기를 변경하는 기능을 지원한다(get_shell_surface()로 wl_surface를 얻은 후) > [1. 리눅스 그래픽 시스템과 Wayland/Weston](https://prographics.tistory.com/2)	8c38ac264bec41f59eb1104934a18768

dual booting

OS Mode

null

1. bitlocker locker 안끄고하면 encrypted 된다 - read linux partitoin - disk internals linux reader > [Paragon Software | Main page](https://www.paragon-drivers.com/en/lfswin/#overview)

24656ee018014e6388b841b9f579c30c

System call

OS Mode

null

# fork() child return 0 parent returns child's pid # exec() make, new → has own main command(shell) executer # wait() to synchronize wait child pid ex. wait(&s) - s go to exit after wait → termination status(child) # exit() exit → exit status

f36194e943f3498593520460b36c55aa

Critical Section

Process Notion

Apr 21, 2021

Alan Jo

Aug 10, 2023

상호배제, 진행, 한정된 대기를 충족

8469b236528b41efb4088ea3a69a4cc4

IPC

Process Notion

Nov 5, 2019

Alan Jo

Seong-lae Cho

Aug 10, 2023

inter process communication Done by kernel (client server model) # basic IPC pipe, named pipe(fifoi) # Advanced IPC massage pussing, semaphore(ipc facilities), shared mem = low levle socket (bsd) oriented ### # internet IPC socket api by packet ### udp - letter - criented ### tcp - phone call - connection oriented

98010a1077fd45968ce78ae98505b2e5

massage passing

Process Notion

Nov 5, 2019

Alan Jo

Seong-lae Cho

Aug 10, 2023

ab22575af94b441caad37d2e1697cd59

Monitor Sync

Process Notion

Nov 5, 2019

Alan Jo

Seong-lae Cho

Aug 10, 2023

Synchronize by using Mutex and Thread-safe **Condition Variables(Queue)** more simpler than Semaphore, because monitor Condition variable do lock and unlock. but Semaphore is done by in its process > 배타동기, 조건동기를 위한 큐가 각각 존재 > > ![](https://www.notion.so/image/https%3A%2F%2Fs3-us-west-2.amazonaws.com%2Fsecure.notion-static.com%2Fdb19c807-b616-411d-9a5a-1cececedaf6a%2Ftemp.jpg?table=block&id=07d2333c-4cc4-45d9-a778-ba9d66b14c42&cache=v2) > >

54b03a3282964bdb88207ec60dfeb1b2

Mutex

Process Notion

Nov 5, 2019

Alan Jo

Seong-lae Cho

Aug 10, 2023

mutex is type variable and has function lock and unlock lock(mutex), unlock(mutex)

cbfff707d2fe484ea20344f1104b7141

Process context

Process Notion

Nov 5, 2019

Alan Jo

Seong-lae Cho

Dec 3, 2022

- program context - kernel context

e76d70c66cd840b4a247de3310e85416

Process control block

Process Notion

Nov 5, 2019

Alan Jo

Seong-lae Cho

Dec 3, 2022

PCB - data registers - PC,SP registers - context

f62e2db348e442c580ea6d2084973973

Process descriptor

Process Notion

Nov 5, 2019

Alan Jo

Seong-lae Cho

Dec 3, 2022

PD - (p)ids, virtual memory structure

81614898a94d48058419b80e9e971fae

Process Exit

Process Notion

May 19, 2023

Alan Jo

May 19, 2023

### Process Exit Code - 137 - Memory Issue - 127 - Command not found

2d82b561fba64541bde82c478297a22c

Process Function Call

Process Notion

Dec 3, 2022

Alan Jo

Dec 3, 2022

[Process Memory](https://texonom.com/process-memory-53285d27582d49058052939d739e8623)

Process Function Call Management ### Process Function Call Notion |Title| |:-:| |[Base Pointer](https://texonom.com/base-pointer-b2e339920fc947749be4e37d6ef87898)| |[Stack pointer](https://texonom.com/stack-pointer-3cba595dc071434eb2c9cf27dad65f57)| |[Activation Record](https://texonom.com/activation-record-9984197a3a144f878d427d71d6052a10)| |[Calling Sequence](https://texonom.com/calling-sequence-aeb9d35a8a714f048530391482503ccd)|

ab41c2af3a5743599fca591ce08b535f

Process image

Process Notion

Nov 5, 2019

Alan Jo

Seong-lae Cho

Dec 3, 2022

- contains kernel space - code - low address - data - stack - heap - high address

c6384d00d1af41a6bcaa1b238165be17

Process Memory

Process Notion

Dec 3, 2022

Alan Jo

Dec 3, 2022

### Process Memory Notion |Title| |:-:| |[Stack Memory](https://texonom.com/stack-memory-70115a2851da415ca2aa913c7c5d3195)| |[Heap Memory](https://texonom.com/heap-memory-30304a87b33848bd97600adaaddbbfff)| |[Memory Model](https://texonom.com/memory-model-8d30211d5095420c82620b3b91be155f)|

53285d27582d49058052939d739e8623

Process State

Process Notion

Nov 5, 2019

Alan Jo

Seong-lae Cho

Dec 3, 2022

### PSM(process state modeling) blocked queue > single blocked queue > multiple blocked queues (queue to event) > io bound system - CPU 에 물려있음 cpu bound system - io 에 물려있음

bbe0f9abe7b240c7a1d2a2d1c3478afd

Process switching

Process Notion

Nov 5, 2019

Alan Jo

Seong-lae Cho

Dec 3, 2022

→ mode(user) swithing - save process state only process swithing - save context(context switch), PCB(control block) → to appropriate queue update state of process → update mm structure

7f2486a6184241fba896860610a4d5f1

Process Sync

Process Notion

Nov 5, 2019

Alan Jo

Seong-lae Cho

Aug 10, 2023

smart person learn knowledge by network data structure but gard to use and administratenormal person learn knowldedge by tree data structure, so cannot imagine creative thinking which connect far distance in tree but close distance in network **so i need to make network document site myself** > critical section: where racing can be ocuurred ## issues Mutual Exclusion (상호배제): no two process execution in critical section Progress: no indefinite postpone while selection of process enter to critical section Bounded Waiting: no starvation # Solution ### 1. Locks - spinlocks - disabling inturrupts > for two-process case code ### Spinlock (software-only) 1. turn onlyping-pong like one-to-one problem 2. flag onlysymultaniously raising flag problem 3. **Peterson's algorithm**use flag and turn variable > ```typerepeat flag[i] := true; turn := j; while (flag[j] and turn = j) //cation to and //busy waiting = spinning critical section flag[i] := false; //else code until false;``` ### spinlock (hardware atomic) by hardware support atomic operation > atomic operation: cannot be disturbed ### disabling interrupts prevent context switches **acquire()/lock()**: before critical section**release()/unlock()**: after critical section # Differences > ### Semaphore > Semaphore prevent multi-process access to data which are File type integer counter > Semaphore - unlock by other > supervise many resources > ![](https://www.notion.so/image/https%3A%2F%2Fs3-us-west-2.amazonaws.com%2Fsecure.notion-static.com%2Fde77dfc5-3c2a-4128-989c-7443486332d9%2Ftemp.jpg?table=block&id=71108d45-8e2a-4fe9-87dc-47519b809e9b&cache=v2) > > ### Mutex > Mutex(mutual exclusion) is object(variable) in process that prevent multi-thread access to data - use locking and unlocking > Mutex - self unlock > mutex is for two process - semaphore is for multi process use critical section > supervise only one resource > ![](https://www.notion.so/image/https%3A%2F%2Fs3-us-west-2.amazonaws.com%2Fsecure.notion-static.com%2F9ed7cd04-daba-4d0a-9a45-b75b72d1e370%2Ftemp.jpg?table=block&id=04dc4d93-4edb-40a4-bab1-868919034830&cache=v2) > All Mutex is Semaphore, Semaphore can be mutex, not all mutexes are Semaphore

45211a317f4f442cbab6b374fdaed630

Semaphore

Process Notion

Nov 5, 2019

Alan Jo

Seong-lae Cho

Aug 10, 2023

### Integer counter (File) variable S - cannot solve all dead lock - default value is resources number ### P function(try / decrement) - before critical section - wait(S) ### V function(increment) - after critical section -signal(S) two function should satisfy atomicity - other process cannot change while this function > 0 : block > ## Method 1 > ```typeP(S) { // do nothing - busy waiting while S <=0; S--; } V(S) { S++; }``` > ## Method 2 > ```typeP(S) { S--; if S < 0 // sleep this process } V(S) { S++; if S <= 0 // remove from sleep queue``` - semval : 세마포어의 값으로서 항상 양수가 지정된다. 여기에 값을 새로 지정하려면 반드시 세마포어 시스템 호출을 통해야하며 프로그램에서 일반 자료형의 변수와 같이 직접 접근 할 수는 없다. - sempid : 세마포어에 접근했던 최근의 프로세스의 프로세스 식별번호이다. - semncnt : 세마포어의 값이 현재보다 증가하기를 기다리는 프로세스의 갯수. - semzcnt : 세마포어의 값이 0으로 되기까지 기다리는 프로세스의 갯수 > >

46b11416972249d2a40e6c3e5060304a

Activation Record

Process Function Call Notion

Dec 3, 2022

Alan Jo

Dec 3, 2022

9984197a3a144f878d427d71d6052a10

Base Pointer

Process Function Call Notion

Dec 3, 2022

Alan Jo

Dec 3, 2022

b2e339920fc947749be4e37d6ef87898

Calling Sequence

Process Function Call Notion

Dec 3, 2022

Alan Jo

Dec 3, 2022

aeb9d35a8a714f048530391482503ccd

Stack pointer

Process Function Call Notion

Dec 3, 2022

Alan Jo

Dec 3, 2022

3cba595dc071434eb2c9cf27dad65f57

Heap Memory

Process Memory Notion

Oct 29, 2020

Alan Jo

Dec 3, 2022

메모리 할당이 이루어지는 곳으로 선언한 변수와 함수들 동적 메모리 할당에 사용 포인터를 사용하여 데이터 위치를 저장 스택과 비교하여 데이터를 처리하고 접근하는 속도는 느리지만, 더 큰 용량의 데이터를 저장 컴파일타임에 메모리 사이즈를 정확히 예측할 수 없다 힙 메모리는 쓰레드간 공유 힙에 저장되는 데이터 종류로는 전역 변수 (global variables), 참조 타입(reference types) 할당된 힙 공간을 초과하는 메모리를 사용하려고 하면 OutOfMemory 에러가 발생 프로그램이 메모리를 더 이상 사용하지 않을 시에는 해당 메모리를 해제(free)해주어야 > [자바스크립트와 V8 엔진의 메모리 관리 프로세스](https://medium.com/naver-place-dev/%EC%9E%90%EB%B0%94%EC%8A%A4%ED%81%AC%EB%A6%BD%ED%8A%B8%EC%99%80-v8-%EC%97%94%EC%A7%84%EC%9D%98-%EB%A9%94%EB%AA%A8%EB%A6%AC-%EA%B4%80%EB%A6%AC-%ED%94%84%EB%A1%9C%EC%84%B8%EC%8A%A4-f45091e696e1)

30304a87b33848bd97600adaaddbbfff

Memory Model

Process Memory Notion

Dec 3, 2022

Alan Jo

Dec 3, 2022

8d30211d5095420c82620b3b91be155f

Stack Memory

Process Memory Notion

Oct 29, 2020

Alan Jo

Dec 3, 2022

[Process](https://texonom.com/process-ffd68f9e2b2648759b96047d48d17778)

### 프로그램의 어디에 있는지를 기록하는 자료 구조 콜스택의 각각은 스택프레임(Stack Frame) 데이터의 크기가 유한(finite)정적(static) 데이터의 크기가 컴파일타임에 계산 함수의 호출 정보 또한 스택 프레임으로 저장 각 프레임은 함수를 호출시 필요로하는 데이터를 저장한 한 블록의 공간을 의미 해당 함수가 새 변수를 생성하면, 그 데이터는 스택 맨 위의 블록에 저장 함수 호출이 종료되면 스택 맨 위 블록이 제거 멀티 스레딩이 가능한 어플리케이션은 스레드 수 만큼 스택을 여러개 일반적으로 스택에 저장되는 데이터 종류로는 지역변수(local variables), 포인터, 함수 프레임 스택에 저장될 수 있는 데이터의 사이즈에 상한이 있으며, 스택의 사이즈를 초과하는 경우에 StackOverflowError 가 발생 [Call Stack](https://texonom.com/call-stack-f041634136c74474bafad41496dff953) [Blowing the stack](https://texonom.com/blowing-the-stack-e20d822b114e4b17add6e5bff28e4a71) [Stack Trace](https://texonom.com/stack-trace-26fd9fe6f37242818d81284ff135c73d) > [자바스크립트와 V8 엔진의 메모리 관리 프로세스](https://medium.com/naver-place-dev/%EC%9E%90%EB%B0%94%EC%8A%A4%ED%81%AC%EB%A6%BD%ED%8A%B8%EC%99%80-v8-%EC%97%94%EC%A7%84%EC%9D%98-%EB%A9%94%EB%AA%A8%EB%A6%AC-%EA%B4%80%EB%A6%AC-%ED%94%84%EB%A1%9C%EC%84%B8%EC%8A%A4-f45091e696e1) [Heap Memory](https://texonom.com/heap-memory-30304a87b33848bd97600adaaddbbfff)

70115a2851da415ca2aa913c7c5d3195

Blowing the stack

Stack Memory

null

콜 스택의 최대 크기에 다다랐을 때

e20d822b114e4b17add6e5bff28e4a71

Call Stack

Stack Memory

null

실제 실행되는 코드를 순서대로 실행하는 곳

f041634136c74474bafad41496dff953

Stack Trace

Stack Memory

null

### 예외가 발생했을 때 콜스택의 상태

26fd9fe6f37242818d81284ff135c73d

**`Device Queue`**

Processor Queues

May 19, 2021

Alan Jo

May 19, 2021

- I/O device의 처리를 기다리는 프로세스의 집합

453d40088668423c96d51003b27f9a2e

**`Job Queue`**

Processor Queues

May 19, 2021

Alan Jo

May 19, 2021

- 현재 시스템 내에 있는 모든 프로세스의 집합

92bccac0db114b5c83a0f3ac0d9de17e

**`Ready Queue`**

Processor Queues

May 19, 2021

Alan Jo

May 19, 2021

- 현재 메모리 내에 있으면서 CPU를 잡아서 실행되기를 기다리는 프로세스의 집합

c8546adf7d604a73a15b292808bef5b7

Processor Dispatcher

Processor Scheduler Notion

May 19, 2021

Alan Jo

May 19, 2021

CPU 스케줄러 내부에 포함된 것 CPU의 제어권을 CPU Scheduler에 의해 선택된 프로세스에게 넘긴다 단기 스케줄러가 선택한 프로세스에 실질적으로 프로세서를 할당하는 역할 프로세스의 레지스터를 적재하고 Context Switching, Kernel Mode에서 User Mode로 전환시켜주며 프로세스가 다시 시작할 때 사용자 프로그램이 올바른 위치를 찾을 수 있도록 latency - to take dispatch overhead > [[O/S] CPU Scheduler와 Dispatcher](https://velog.io/@ss-won/OS-CPU-Scheduler%EC%99%80-Dispatcher)

dac6ca05f13c4ddc82906bd73f6080df

Long-term scheduler

Processor Schedulers

May 19, 2021

Alan Jo

May 19, 2021

job scheduler

5f0783472fa94c478b10b7a1bfbf0192

Medium-term scheduler

Processor Schedulers

May 19, 2021

Alan Jo

May 19, 2021

Swapper

15b70c90c2f641e696fcc6c90cbd04d9

Short-term scheduler

Processor Schedulers

May 19, 2021

Alan Jo

May 19, 2021

CPU scheduler

f95f24cbd78d490c8a216dcabb04e4cb

CAS

Blocking

null

### compare-and-swap

b3541e0665b74cf7aa4f91a7b202fde2

Deadlock

Thread Notion

Nov 5, 2019

Alan Jo

Seong-lae Cho

Apr 3, 2023

# To-do - [ ] update last recovery part Deadlock problem -** A set **of blocked processes each holding a resource and waiting to acquire a resource held by another process in the set > - Has a set of processes > - Has a set of resources > - deadlocks can occur across machines (between I/O processes) > Paradigm of resource usage by process → > ![](https://www.notion.so/image/https%3A%2F%2Fs3-us-west-2.amazonaws.com%2Fsecure.notion-static.com%2Feb2997df-06f0-4a58-a3ab-8a260766ca4c%2FUntitled.png?table=block&id=b09cf27f-fd2c-4fde-ac6b-6e47c6f16cad&cache=v2) > ex. - semaphores A and B, initialized to 1 > - P1 and P2 each hold one tape drive and each needs another one > ![](https://www.notion.so/image/https%3A%2F%2Fs3-us-west-2.amazonaws.com%2Fsecure.notion-static.com%2F295577a4-2317-41fe-a9f6-1189a2a6234b%2FUntitled.png?table=block&id=2c8323b5-ea0d-4f36-afe3-5e629c1ac5a5&cache=v2) > Deadlock problem is important in special purpose OS # Bridge Crossing > - it can be resolved if one car backs up - preempt resources and rollback > - Several cars may have to be backed up(kill process) if a deadlock occurs > - Starvation is possible > ![](https://www.notion.so/image/https%3A%2F%2Fs3-us-west-2.amazonaws.com%2Fsecure.notion-static.com%2Fb18b9b81-b9ab-4d66-b14c-c7d635c684c2%2FUntitled.png?table=block&id=a0e07da0-3140-4acf-9739-fcbee231f253&cache=v2) > Kill process need restart process - Why? # Resource Allocation Graph > $$G = (V, E).$$ > Model tuple of the state of a computer system as a directed graph > **Request edge** : process to resource (not to special one resource set itself) > **Allocation edge **: resource to process > > ![](https://www.notion.so/image/https%3A%2F%2Fs3-us-west-2.amazonaws.com%2Fsecure.notion-static.com%2F0b47c6e3-caf9-44ec-822a-2bb25517d3e1%2FUntitled.png?table=block&id=bb437e11-4e02-4313-a5e3-a4af541a760e&cache=v2) > ## Theorem 1 > **If a graph does not contain a cycle then no processes are deadlocked** > ## Theorem 2 > **If there is only a “single” instance per resource type, then a set of processes are deadlocked if and only if the processes and resources form a cycle in the resource allocation graph** ## “Necessary” Conditions for a Deadlock **Deadlock can arise if the following four conditions hold simultaneously - at the same time** 1. **Mutual exclusion** : only one process at a timfe can use a resource. 2. **Hold and wait** : a process holding at least one resource is waiting to acquire additional resources held by other processes. 3. **No preemption **: a resource can be released only voluntarily by the process holding it. 4. **Circular wait : **a cycle in the resource allocation graph ### So we will not make this conditions simultaneously by Handling Deadlocks > theorem 2 is only enable sufficient condition ## Method 1: Deadlock Prevention **Ensure that one of the four deadlock conditions never occur ← make one false among 4 (not about information, policy and data structure change)** <details><summary> 1 → make shareable share</summary> make mutual exclusive available resources to not exclusively is impossible → Must hold for non-shareable resources </details> <details><summary> 2 → **No wait or No hold **(resources utilization become low, starvation possible)</summary> Guarantee that whenever a process requests a resource, it does not hold any other resources Require process to request and be allocated “all” its resources before it begins execution, or allow process to request resources only when the process has “none”. </details> <details><summary> 3 → become preemptive (stop while processing)</summary> If a process that is holding some resources requests another resource that cannot be immediately allocated to it, then all resources currently being held are released Preempted resources are added to the list of available resources Process will be restarted only when it can regain its old resources, as well as the new ones that it is requesting Can be applied to resources whose state can be easily saved and restored later : e.g. CPU registers, memory, … </details> <details><summary> 4 → remove cycle (if no resources can be substituted → Theorem 2) **most used method**</summary> Impose a total **ordering of all resource types**, and require that each process **requests resources in order **of enumeration </details> ## Method 2: Deadlock Avoidance **Avoid deadlock by run-time checking and allocation of resources - check before allocate (never enter an unsafe state)** <details><summary> **Requires** that the system has some additional a **priori information **and **algorithm**</summary> Simplest and most useful model requires that each process declare the** maximum number of resources** of each type that it may need **The deadlock-avoidance algorithm dynamically examines the “resource-allocation state” to ensure that there can never be a circular-wait condition** </details> - **Safe State** : System is in safe state if there exists a **safe sequence** of all processes **requests resource → decide immediate allocation leaves the system in a “safe” state** > **Resource-allocation state **is defined by the number of available and allocated resources, and the maximum demands of the processes ### Then How can we do that by what algorithm? if resource is single instance → use resource allocation graph and check cycle > **if resource is multiple instance →** > > [Banker's algorithm](https://texonom.com/bankers-algorithm-a3e9530ac45b4c61806354379b55c593) > ## Method 3: Deadlock Detection and Recovery **Let the system deadlock and then deal with it (No a priori information, algorithm exist)** ### **Detection Algorithm** Request: an n x m matrix indicates the current request of each process (Replace Need with Request matrix) - it is safety algorithm in banker's algorithm > usually each process is not assumed to have knowledge in its maximum use **Then how often we will invoke algorithm - have no answer** ## Recovery from Deadlock <details><summary> **Methods of recovery**</summary> </details> 5. Process terminate - lose all process, not easy to recover process done 6. resource preemption > - Selecting a victim, rollback, starvation is an issue > ![](https://www.notion.so/image/https%3A%2F%2Fs3-us-west-2.amazonaws.com%2Fsecure.notion-static.com%2F7bc1d018-01cc-425b-a17c-ec7615a6adb2%2FUntitled.png?table=block&id=60291423-d42a-4d02-a3e5-ed94f7618e42&cache=v2) > **if resource is multiple instance → D**etection algorithm like banker's algorithm > caution of starvation → aging > need to kill cause process → re-deadlock > Rollback - 최소한 싸이클이 없어질 만큼의 프로세스는 죽여야 한다. > wait for 그래프는 어떤 프로세스가 어떤 리소스를 wait하고 있는가만 체크한다. 싸이클이 발생했으면 데드락이 발생 한 것이다. > if resource is single instance → check wait-for graph 주깆거 ### Method 4: No policy Ignore the problem and pretend that deadlocks never occur in the system → just reboot Used by most operating systems, including UNIX and Windows ← too much overhead # Reference - Refer Lock hierarchy > [DeadLock](https://ozt88.tistory.com/35)

8c118f296cc1477aac5c59c75cec8235

kernel level thead

Thread Notion

Nov 5, 2019

Alan Jo

Seong-lae Cho

May 11, 2021

498f95b4e748492b8e2ed535bf987b0b

Lock convoy

Thread Notion

Nov 5, 2019

Alan Jo

Seong-lae Cho

May 11, 2021

Lock을 소유하길 기다리는 비율이 Lock을 해제하는 비율보다 높은 것 Lock Convoy가 발생하게 되면 시스템의 성능이 급격하게 떨어지게

a904af475dcb4bb8a0d99ea8e095de39

Priority Inversion

Thread Notion

Mar 28, 2021

Alan Jo

May 11, 2021

윈도우 운영체제에서 Thread에는 항상 우선순위라는 것이 있고, 윈도우 운영체제는 항상 우선순위가 높은 Thread만 실행시키는 스케줄링 정책을 사용 여러개의 우선순위가 lock 과 엮어서 발생하는 성능저하

beb6115d6154481db836a5677f877581

Thread Safe

Thread Notion

May 11, 2021

Alan Jo

May 11, 2021

a6b8ab6ec6e146deafa86b428e5ecfbe

Threads model

Thread Notion

Mar 28, 2021

Alan Jo

May 11, 2021

- one to one - n to n

800491618af24626b02f701d43578b66

Threads Scheduling

Thread Notion

Nov 5, 2019

Alan Jo

Seong-lae Cho

May 11, 2021

Local Scheduling Global Scheduling

e1315fdaa06740c6ab54f097edeba1d7

Two-Step Dance

Thread Notion

Mar 28, 2021

Alan Jo

May 11, 2021

불필요한 Context Switch를 발생

b328c6d4bef8483a97e076bbc91b0be8

Banker's algorithm

Deadlock

null

### It is Deadlock Avoidance itself **Define a set of vectors and matrices that characterize the current state of all resources and processes** > Each process must a priori claim maximum use # DataStructure - n - process number, m resource **type **number. - **Available** : one dimension array of length m - store available resources number by resource **type** - **Max** (require to retire process): two dimension array of m x n - process i require j type and express it by max[i,j] - **Allocation** : two dimension array of m x n - how much allocated - allocation[i,j] - **Need** : two dimension array of m x n - **(Need = Max - Allocation) how much more need** ### Banker's algorithm is function of input **Request** Request_i : one dimension array of length m - request vector for process Pi ![](https://www.notion.so/image/https%3A%2F%2Fs3-us-west-2.amazonaws.com%2Fsecure.notion-static.com%2F7b38698d-432a-474a-bdde-51b3874c093e%2FUntitled.png?table=block&id=48f55dad-e108-4519-8bff-2aea677cb0f5&cache=v2) # Safety Algorithm **Work(copy of Available) **and **Finish(initialized false for all process) **be vectors of length m and n, respectively → fine sequence of execution ### Result is no → process must wait ## Difference All tow algorithm is Deterministic Algorithm but Banker's is determine for Allocation Detection is determine of checking deadlock - Banker's Algorithm is virtual verification of unassigned resource by simulation - Detection Algorithm is check stage is safe or not

a3e9530ac45b4c61806354379b55c593

user level thread

Thread Types

Nov 5, 2019

Alan Jo

Seong-lae Cho

May 11, 2021

6f68e5d2dff240359b9b494534598b29

Processor Scheduling Algorithm

Processor Scheduling Usages

May 19, 2021

Alan Jo

Feb 21, 2023

### Processor Scheduling Algorithms |Title| |:-:| |[FCFS](https://texonom.com/fcfs-edf5b1ac74e8471fa9e35f31239295ba)| |[SJF](https://texonom.com/sjf-0cf78004bc7848a69e2f1aa607a20e02)| |[Round Robin](https://texonom.com/round-robin-45c43acd37de47f88881d01d9e3eb925)| |[Multilevel Queue](https://texonom.com/multilevel-queue-123add4d32274321a8643d4e927b52cc)| |[Multilevel Feedback Queue](https://texonom.com/multilevel-feedback-queue-ee4381e712ad4f869e3523655e84bd16)|

305e26d3aca84cdd9e5c980e91642a8f

Processor Scheduling Evaluation

Processor Scheduling Usages

May 19, 2021

Alan Jo

Feb 21, 2023

Queueing Model Implementation & Measurement Simulation > [[OS] 5-2. CPU Scheduling II](https://asfirstalways.tistory.com/124)

b897d00ffba948e6922c062d95693455

Processor Scheduling Method

Processor Scheduling Usages

May 19, 2021

Alan Jo

Feb 21, 2023

### Processor Scheduling Methods |Title| |:-:| |[Multi Processor Scheduling](https://texonom.com/multi-processor-scheduling-7e3b60b954004bb098a7c70ee46677ad)| |[Homogeneous Processor Scheduling](https://texonom.com/homogeneous-processor-scheduling-b643b19e38da4a5a920fd860364fa082)| |[Load Sharing](https://texonom.com/load-sharing-6bb863d9c38f4e628781db57c1345107)| |[Symmetric Multi Processor](https://texonom.com/symmetric-multi-processor-b3d5801f4b80479bb71fdb7f737d0255)| |[Asymmetric Multi Processor](https://texonom.com/asymmetric-multi-processor-0e36cbc355d54549887b513bfb752d8d)| |[Real time Sharing](https://texonom.com/real-time-sharing-2a9baa85c15947b5a8032f20a51590d1)|

c5c243a128b74b2183508330aec1090c

FCFS