Figure 6.1 System layers

Transcription

1 Figure 6.1 System layers Applications, services Middleware OS: kernel, libraries & servers OS1 Processes, threads, communication,... OS2 Processes, threads, communication,... Platform Computer & network hardware Computer & network hardware Node 1 Node 2 Instructor s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3 Pearson Education

2 Figure 6.2 Core OS functionality Process manager Communication manager Thread manager Memory manager Supervisor Instructor s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3 Pearson Education

3 Figure 6.3 Address space 2 N Auxiliary regions Stack Heap 0 Text Instructor s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3 Pearson Education

4 Figure 6.4 Copy-on-write Process A s address space Process B s address space RA RB copied from RA RB Kernel A's page table Shared frame B's page table a) Before write b) After write Instructor s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3 Pearson Education

5 Figure 6.5 Client and server with threads Thread 1 generates results T1 Thread 2 makes requests to server Receipt & queuing Input-output Requests N threads Client Server Instructor s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3 Pearson Education

6 Figure 6.6 Alternative server threading architectures (see also Figure 6.5) workers per-connection threads per-object threads I/O remote objects remote objects I/O remote objects a. Thread-per-request b. Thread-per-connection c. Thread-per-object Instructor s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3 Pearson Education

7 Figure 6.7 State associated with execution environments and threads Execution environment Address space tables Communication interfaces, open files Semaphores, other synchronization objects List of thread identifiers Thread Saved processor registers Priority and execution state (such as BLOCKED) Software interrupt handling information Execution environment identifier Pages of address space resident in memory; hardware cache entries Instructor s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3 Pearson Education

8 Figure 6.8 Java thread constructor and management methods Thread(ThreadGroup group, Runnable target, String name) Creates a new thread in the SUSPENDED state, which will belong to group and be identified as name; the thread will execute the run() method of target. setpriority(int newpriority), getpriority() Set and return the thread s priority. run() A thread executes the run() method of its target object, if it has one, and otherwise its own run() method (Thread implements Runnable). start() Change the state of the thread from SUSPENDED to RUNNABLE. sleep(int millisecs) Cause the thread to enter the SUSPENDED state for the specified time. yield() Enter the READY state and invoke the scheduler. destroy() Destroy the thread. Instructor s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3 Pearson Education

9 Figure 6.9 Java thread synchronization calls thread.join(int millisecs) Blocks the calling thread for up to the specified time until thread has terminated. thread.interrupt() Interrupts thread: causes it to return from a blocking method call such as sleep(). object.wait(long millisecs, int nanosecs) Blocks the calling thread until a call made to notify() or notifyall() on object wakes the thread, or the thread is interrupted, or the specified time has elapsed. object.notify(), object.notifyall() Wakes, respectively, one or all of any threads that have called wait() on object. Instructor s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3 Pearson Education

10 Figure 6.10 Scheduler activations Process A Process B Process P added SA preempted SA unblocked Kernel SA blocked Virtual processors Kernel P idle P needed A. Assignment of virtual processors to processes B. Events between user-level scheduler & kernel Key: P = processor; SA = scheduler activation Instructor s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3 Pearson Education

11 Figure 6.11 Invocations between address spaces (cont d on next slide) (a) System call Thread Control transfer via trap instruction User Kernel Control transfer via privileged instructions (b) RPC/RMI (within one computer) Protection domain boundary Thread 1 Thread 2 User 1 Kernel User 2 Instructor s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3 Pearson Education

12 Figure 6.11 (cont d) Invocations between address spaces (c) RPC/RMI (between computers) Thread 1 Network Thread 2 User 1 User 2 Kernel 1 Kernel 2 Instructor s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3 Pearson Education

13 Figure 6.12 RPC delay against parameter size RPC delay Packet size Requested data size (bytes) Instructor s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3 Pearson Education

14 Figure 6.13 A lightweight remote procedure call Client Server A stack A 1. Copy args 4. Execute procedure and copy results User stub stub Kernel 2. Trap to Kernel 3. Upcall 5. Return (trap) Instructor s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3 Pearson Education

15 Figure 6.14 Times for serialised and concurrent invocations Serialised invocations Concurrent invocations process args marshal Send Receive unmarshal process results process args marshal Send transmission process args marshal Send process args marshal Receive Send unmarshal execute request marshal Send Receive unmarshal process results Receive unmarshal process results Receive unmarshal execute request marshal Send Receive unmarshal execute request marshal Send Receive unmarshal execute request marshal Send time Receive unmarshal process results Client Server Client Server Instructor s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3 Pearson Education

16 Figure 6.15 Monolithic kernel and microkernel S4... S1 S2 S3... S1 S2 S3 S4... Key: Server: Monolithic Kernel Kernel code and data: Microkernel Dynamically loaded server program: Instructor s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3 Pearson Education

17 Figure 6.16 The role of the microkernel Middleware Language support subsystem Language support subsystem OS emulation subsystem... Microkernel Hardware The microkernel supports middleware via subsystems Instructor s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3 Pearson Education