Multiple Processor SystemsMultiprocessor SystemsMultiprocessorsMultiprocessor Hardware (1)Multiprocessor Hardware (2)Multiprocessor Hardware (3)Multiprocessor Hardware (4)Multiprocessor Hardware (5)Multiprocessor Hardware (6)Multiprocessor OS Types (1)Multiprocessor OS Types (2)Multiprocessor OS Types (3)Multiprocessor Synchronization (1)Multiprocessor Synchronization (2)Multiprocessor Synchronization (3)Multiprocessor Scheduling (1)Multiprocessor Scheduling (2)Multiprocessor Scheduling (3)Multiprocessor Scheduling (4)Multiprocessor Scheduling (5)MulticomputersMulticomputer Hardware (1)Multicomputer Hardware (2)Multicomputer Hardware (3)Low-Level Communication Software (1)Low-Level Communication Software (2)User Level Communication SoftwareRemote Procedure Call (1)Remote Procedure Call (2)Distributed Shared Memory (1)Distributed Shared Memory (2)Distributed Shared Memory (3)Multicomputer Scheduling Load Balancing (1)Load Balancing (2)Load Balancing (3)Distributed Systems (1)Distributed Systems (2)Network Hardware (1)Network Hardware (2)Network Services and Protocols (1)Network Services and Protocols (2)Document-Based Middleware (1)Document-Based Middleware (2)File System-Based Middleware (1)File System-Based Middleware (2)File System-Based Middleware (3)File System-Based Middleware (4)Shared Object-Based Middleware (1)Shared Object-Based Middleware (2)Shared Object-Based Middleware (3)Shared Object-Based Middleware (4)Shared Object-Based Middleware (5)Coordination-Based Middleware (1)Coordination-Based Middleware (2)Coordination-Based Middleware (3)Multiple Processor SystemsChapter 88.1 Multiprocessors 8.2 Multicomputers 8.3 Distributed systemsMultiprocessor Systems•Continuous need for faster computers–shared memory model–message passing multiprocessor–wide area distributed systemMultiprocessorsDefinition:A computer system in which two or more CPUs share full access to a common RAM4Multiprocessor Hardware (1)Bus-based multiprocessorsMultiprocessor Hardware (2)•UMA Multiprocessor using a crossbar switchMultiprocessor Hardware (3)•UMA multiprocessors using multistage switching networks can be built from 2x2 switches (a) 2x2 switch (b) Message formatMultiprocessor Hardware (4)•Omega Switching NetworkMultiprocessor Hardware (5)NUMA Multiprocessor Characteristics1. Single address space visible to all CPUs2. Access to remote memory via commands-LOAD-STORE3. Access to remote memory slower than to localMultiprocessor Hardware (6)(a) 256-node directory based multiprocessor(b) Fields of 32-bit memory address(c) Directory at node 36Multiprocessor OS Types (1)Each CPU has its own operating systemBusMultiprocessor OS Types (2)Master-Slave multiprocessorsBusMultiprocessor OS Types (3)•Symmetric Multiprocessors–SMP multiprocessor modelBusMultiprocessor Synchronization (1)TSL instruction can fail if bus already lockedMultiprocessor Synchronization (2)Multiple locks used to avoid cache thrashingMultiprocessor Synchronization (3)Spinning versus Switching•In some cases CPU must wait–waits to acquire ready list•In other cases a choice exists–spinning wastes CPU cycles–switching uses up CPU cycles also–possible to make separate decision each time locked mutex encounteredMultiprocessor Scheduling (1)•Timesharing–note use of single data structure for schedulingMultiprocessor Scheduling (2)•Space sharing–multiple threads at same time across multiple CPUsMultiprocessor Scheduling (3)•Problem with communication between two threads–both belong to process A–both running out of phaseMultiprocessor Scheduling (4)•Solution: Gang Scheduling1. Groups of related threads scheduled as a unit (a gang)2. All members of gang run simultaneously•on different timeshared CPUs3. All gang members start and end time slices togetherMultiprocessor Scheduling (5)Gang SchedulingMulticomputers•Definition:Tightly-coupled CPUs that do not share memory•Also known as –cluster computers–clusters of workstations (COWs)Multicomputer Hardware (1)•Interconnection topologies(a) single switch(b) ring(c) grid(d) double torus(e) cube(f) hypercubeMulticomputer Hardware (2)•Switching scheme–store-and-forward packet switchingMulticomputer Hardware (3)Network interface boards in a multicomputerLow-Level Communication Software (1)•If several processes running on node –need network access to send packets …•Map interface board to all process that need it•If kernel needs access to network …•Use two network boards–one to user space, one to kernelLow-Level Communication Software (2)Node to Network Interface Communication•Use send & receive rings•coordinates main CPU with on-board CPUUser Level Communication Software•Minimum services provided–send and receive commands•These are blocking (synchronous) calls(a) Blocking send call(b) Nonblocking send callRemote Procedure Call (1)•Steps in making a remote procedure call–the stubs are shaded grayRemote Procedure Call (2)Implementation Issues•Cannot pass pointers–call by reference becomes copy-restore (but might fail)•Weakly typed languages–client stub cannot determine size•Not always possible to determine parameter types•Cannot use global variables–may get moved to remote machineDistributed Shared Memory (1)•Note layers where it can be implemented–hardware–operating system–user-level softwareDistributed Shared Memory (2)Replication(a) Pages distributed on 4 machines(b) CPU 0 reads page 10(c) CPU 1 reads page 10Distributed Shared Memory (3)•False Sharing•Must also achieve sequential consistencyMulticomputer SchedulingLoad Balancing (1)•Graph-theoretic deterministic algorithmProcessLoad Balancing (2)•Sender-initiated distributed heuristic algorithm–overloaded senderLoad Balancing (3)•Receiver-initiated distributed heuristic algorithm–under loaded receiverDistributed Systems (1)Comparison of three kinds of multiple CPU systemsDistributed Systems (2)Achieving uniformity with middlewareNetwork Hardware (1)•Ethernet(a) classic Ethernet(b) switched EthernetComputer(a)(b)Network Hardware (2)The InternetNetwork Services and Protocols (1)Network ServicesNetwork Services and Protocols (2)•Internet Protocol•Transmission Control Protocol•Interaction of protocolsDocument-Based Middleware (1)•The Web–a big directed graph of documentsDocument-Based Middleware (2)How the browser gets a page1. Asks DNS for IP address2. DNS replies with IP address3. Browser makes connection 4.