Computer Science and Engineering Copyright by Hesham El-Rewini Advanced Computer Architecture CSE 8383 April 6, 2006 Session 22

Computer Science and Engineering Copyright by Hesham El-Rewini Contents Communication Patterns Message Passing in PVM (Section 8.4) Network Computing (Chapter 7)

Computer Science and Engineering Copyright by Hesham El-Rewini Routing Efficiency Two Parameters Channel Traffic (number of channels used to deliver the message involved) Communication Latency (distance)

Computer Science and Engineering Copyright by Hesham El-Rewini Multicast on a mesh (5 unicasts) Traffic ? Latency ?

Computer Science and Engineering Copyright by Hesham El-Rewini Multicast on a mesh (multicast pattern 1) Traffic ? Latency ?

Computer Science and Engineering Copyright by Hesham El-Rewini Multicast on a mesh (multicast pattern 2) Traffic ? Latency ?

Computer Science and Engineering Copyright by Hesham El-Rewini Broadcast (tree structure)

Computer Science and Engineering Copyright by Hesham El-Rewini Message Passing in PVM (Revisit) User application Library Daemon User application Library Daemon Sending TaskReceiving Task

Computer Science and Engineering Copyright by Hesham El-Rewini Standard PVM asynchronous communication A sending task issues a send command (point 1) The message is transferred to the daemon (point 2) Control is returned to the user application (points 3 & 4) The daemon will transmit the message on the physical wire sometime after returning control to the user application (point 3)

Computer Science and Engineering Copyright by Hesham El-Rewini Standard PVM asynchronous communication (cont.) The receiving task issues a receive command (point 5) at some other time In the case of a blocking receive, the receiving task blocks on the daemon waiting for a message (point 6). After the message arrives, control is returned to the user application (points 7 & 8) In the case of a non-blocking receive, control is returned to the user application immediately (points 7 & 8)

Computer Science and Engineering Copyright by Hesham El-Rewini Send (3 steps) 1. A send buffer must be initialized 2. The message is packed into the buffer 3. The completed message is sent to its destination(s)

Computer Science and Engineering Copyright by Hesham El-Rewini Receive (2 steps) 1. The message is received 2. The received items are unpacked

Computer Science and Engineering Copyright by Hesham El-Rewini Message Buffers Buffer Creation (before packing) Bufid = pvm_initsend(encoding_option) Bufid = pvm_mkbuf(encoding_option) Encoding optionMeaning 0XDR 1No encoding 2Leave data in place

Computer Science and Engineering Copyright by Hesham El-Rewini Message Buffers (cont.) Data Packing pvm_pk*() pvm_pkstr() – one argument pvm_pkstr(“This is my data”); Others – three arguments 1. Pointer to the first item 2. Number of items to be packed 3. Stride pvm_pkint(my_array, n, 1); Packing functions can be called multiple times to pack data into a single message

Computer Science and Engineering Copyright by Hesham El-Rewini Sending a message Point to point (one receiver) info = pvm_send(tid, tag) broadcast (multiple receivers) info = pvm_mcast(tids, n, tag) info = pvm_bcast(group_name, tag) Pack and Send (one step) info = pvm_psend(tid, tag, my_array, length, data type)

Computer Science and Engineering Copyright by Hesham El-Rewini Receiving a message Blocking bufid = pvm_recv(tid, tag) -1  wild card in either tid or tag Nonblocking bufid = pvm_nrecv(tid, tag) bufid = 0 (no message was received) Timeout bufid = pvm_trecv(tid, tag, timeout) bufid = 0 (no message was received)

Computer Science and Engineering Copyright by Hesham El-Rewini Different Receive in PVM Pvm_recv() wait Time Funciton is called Time is expired Message arrival Blocking Pvm_nrecv() Continue execution Non-blocking Pvm_trecv() wait Timeout Resume execution

Computer Science and Engineering Copyright by Hesham El-Rewini Data unpacking pvm_upk*() pvm_upkstr() – one argument pvm_upkstr(string); Others – three arguments 1. Pointer to the first item 2. Number of items to be unpacked 3. Stride pvm_upkint(my_array, n, 1);

Computer Science and Engineering Copyright by Hesham El-Rewini Networks Computing Four categories WAN MAN LAN SAN Internet TCP/IP

Computer Science and Engineering Copyright by Hesham El-Rewini Other Network technologies Fast Ethernet and Gigabit Ethernet The Fiber Distributed Data Interface (FDDI) High-Performance Parallel Interface (HIPPI) Asynchronous Transfer Mode (ATM) Scalable Coherent Interface (SCI)

Computer Science and Engineering Copyright by Hesham El-Rewini HiPPI ATM 10 Base T 100 Base T SCI SANLANMAN WAN 10Mbps 100Mbps 1000Mbps 10Gbps 1000 Base T FDDI A representation of network technologies

Computer Science and Engineering Copyright by Hesham El-Rewini Client/Server Systems Interconnection Network Interconnection Network Server Threads Client Server Client

Computer Science and Engineering Copyright by Hesham El-Rewini Sockets Sockets are used to provide the capability of making connections from one application running on one machine to another running on a different machine. Once a socket is created, it can be used to wait for an incoming connection (passive socket) or can be used to initiate connection (active socket). Client Serve r A Socket Connection

Computer Science and Engineering Copyright by Hesham El-Rewini A Client Server Framework for Parallel Applications Interconnection Network Interconnection Network Master (Supervisor) Server 1 Server 2 Server 3Server n Client Slaves (Workers)

Computer Science and Engineering Copyright by Hesham El-Rewini Computer Clusters  Advances in commodity processors and network technology  Network of PCs and workstations connected via LAN or WAN forms a Parallel System  Compete favorably (cost/performance)

Computer Science and Engineering Copyright by Hesham El-Rewini Cluster Architecture M C P I/O OS M C P I/O OS M C P I/O OS Middleware Programming Environment Interconnection Network Home cluster

Computer Science and Engineering Copyright by Hesham El-Rewini Internet Grids Dependable, consistent, pervasive, and inexpensive access to high end computing. Geographically distributed platforms.