Concurrent Systems II - Bad Request - Trinity College Dublin

More documents

Recommendations

Info

Second Attempt • Two processes, p and q, each with their own ‘want’ variables wantp and wantq. • If a process wants to enter its critical section, it ensures the other process’ want variable is false and then asserts its own while its entering, is in, and is leaving its critical region. 108 Trinity College Dublin © Mike Brady 2007–2009
Attempt #2 Critical Section Problem Attempt #2 boolean wantp ← false, wantq ← false loop forever p loop forever q p1: non-critical section q1: non-critical section p2: await wantq = false q2: await wantp = false p3: wantp ← true q3: wantq ← true p4: critical section q4: critical section p5: wantp ← false q5: wantq ← false Do you have an intuition about what might happen? 109 Trinity College Dublin © Mike Brady 2007–2009
Page 1 and 2:
Concurrent Systems II (CS3D4/CS3BA2
Page 3 and 4:
POSIX Threads • POSIX Threads aka
Page 5 and 6:
Six Separate Threads Master Thread
Page 7 and 8:
Where… • ‘thread’ is the ID
Page 9 and 10:
Hello World -- Creating Threads int
Page 11 and 12:
Hello World -- Thread Function void
Page 13 and 14:
Wilde/Stoker/Ubuntu h-3.1$ cc -lpth
Page 15 and 16:
Interaction • No thread interacti
Page 17 and 18:
Interactions & Dependencies • Int
Page 19 and 20:
…to do Parallel Programming • H
Page 21 and 22:
Hardware Main Memory Level 2 Cache
Page 23 and 24:
Shared Memory Machine • Each proc
Page 25 and 26:
Concurrent Program • A Concurrent
Page 27 and 28:
Communication • A parallel progra
Page 29 and 30:
1 - Flow Dependence S1: write to lo
Page 31 and 32:
3 - Output Dependence S1: write to
Page 33 and 34:
Dependence in Loops j k k i 1 2 j 5
Page 35 and 36:
How can we transform it? • We can
Page 37 and 38:
Issues: • The variable sum, as wr
Page 39 and 40:
Summarising: • We could paralleli
Page 41 and 42:
Example • Sample function: y = 0.
Page 43 and 44:
Synchronisation • We’ve looked
Page 45 and 46:
Shared Variable S: Thread 1 after T
Page 47 and 48:
Mutual Exclusion in pthreads. • M
Page 49 and 50:
Shared Variable S Protected by Mute
Page 51 and 52:
Lock and Unlock Mutex • pthread_m
Page 53 and 54:
} /********** Critical Section ****
Page 55 and 56:
Problem Tutorial • The transpose
Page 57 and 58: Producers and Consumers • Essenti
Page 59 and 60: Condition Variables (2) • Dramati
Page 61 and 62: From Thread U’s POV (2) • If C
Page 63 and 64: From Thread U’s POV (4) • Acqui
Page 65 and 66: Thread S (2) • Acquire Mutex M
Page 67 and 68: Semaphores • Computer Semaphores
Page 69 and 70: Semaphore Consumer ◾Acquire Mutex
Page 71 and 72: Semaphores (3) • Useful for count
Page 73 and 74: Sample Solution for ∏ • Calcula
Page 75 and 76: unsigned long long clock_cycles() {
Page 77 and 78: The Challenge of Concurrency • Co
Page 79 and 80: Concurrent Execution • A concurre
Page 81 and 82: Notation Trivial Concurrent Program
Page 83 and 84: Trivial Concurrent Program p1: n
Page 85 and 86: Example — Jumping Frogs • A fro
Page 87 and 88: If the frogs can only move “forwa
Page 89 and 90: State Diagrams for Processes • A
Page 91 and 92: Book Reference Principles of concur
Page 93 and 94: Correctness • (Correctness in Seq
Page 95 and 96: Using State machines • We can des
Page 97 and 98: The Critical Section Problem (2)
Page 99 and 100: Observations & Implications • Rem
Page 101 and 102: Simplify Critical Section Problem i
Page 103 and 104: State Transitions r1,s1,1 r1: await
Page 105 and 106: Deadlock Free? • Deadlock Free: I
Page 107: Scorecard Mutual Exclusion Deadlock
Page 111 and 112: Attempt #2 Fails… • Attempt 2 f
Page 113 and 114: Attempt #3 Critical Section Problem
Page 117 and 118: Attempt #4 loop forever Critical Se
Page 121 and 122: Attempt #5, derived from #4 Critica
Page 123 and 124: Verification of concurrent programs
Page 125 and 126: A quick overview of some mathematic
Page 127 and 128: A quick overview of some mathematic
Page 129 and 130: Proving correctness by induction
Page 131 and 132: A quick overview of some temporal l
Page 133 and 134: A quick overview of some temporal l
Page 135 and 136: Temporal logic at work • Consider
Page 137 and 138: Promela • Promela [Protocol/Proce
Page 139 and 140: Process (2) • A process type (pro
Page 141 and 142: SPIN Hello World Example SPIN = Sim
Page 143 and 144: Promela Variables (2) • Arrays
Page 145 and 146: Statements (2) • The skip stateme
Page 147 and 148: If Statement if :: (n % 2 != 0) ->
Page 149 and 150: Atomic Statement atomic { stat1; st
Page 151 and 152: Process Execution / Evaluation Sema
Page 153 and 154: The Closed World Assumption • The
Page 155 and 156: Process memory management • In a
Page 157 and 158: Virtual memory • Give each proces
Page 159 and 160:
Virtual memory 0 0 process 1 2 32 0
Page 161 and 162:
Memory management requirements and
Page 163 and 164:
E.g. Virtual memory implementation
Page 165 and 166:
Multi-level page tables Virtual add
Page 167 and 168:
Typical process memory layout memor
Page 169 and 170:
Translation look aside buffer • E
Page 171 and 172:
Page fault handling Start Access pa
Page 173 and 174:
Fetch policy • When should a page
Page 175 and 176:
Page replacement policy • A page
Page 177 and 178:
Page replacement policy • First-I
Page 179 and 180:
Clock Algorithm 179 Trinity College
Page 181 and 182:
Resident set management • Variabl
Page 183 and 184:
Resident set management Local Repla
Page 185 and 186:
Resident set management Δ Working
Page 187 and 188:
Resident set management 187 Trinity
Page 189 and 190:
Cleaning policy • Page buffering
Page 191 and 192:
Load control • We can use a few d
Page 193 and 194:
Process state transitions • Proce
Page 195 and 196:
Preemptive and nonpreemptive schedu
Page 197 and 198:
Scheduling algorithms • First-Com
Page 199 and 200:
Scheduling algorithms • Shortest-
Page 201 and 202:
Scheduling algorithms • Priority
Page 203 and 204:
Scheduling algorithms • Round-Rob
Page 205 and 206:
Example Process Arrival Time Next B
Page 207 and 208:
Scheduling algorithms • Multi-lev
Page 209 and 210:
Scheduling algorithms • Multi-lev
Page 211 and 212:
Multi-processor scheduling • Flyn
Page 213 and 214:
Layered file I/O (1) Application Di
Page 215 and 216:
Disk access • Disks are slow ◾
Page 217 and 218:
Disk scheduling • So, the order i
Page 219 and 220:
Disk scheduling algorithms (2) •
show all

Concurrent Systems II - Bad Request - Trinity College Dublin

Create successful ePaper yourself

Delete template?

Save as template?