Parallel Programming using PVM

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Parallel Programming using PVM (Parallel Virtual
Machines) Douglas Moore 10 November 2003 CS
775 Distributed Systems
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• PVM Parallel Virtual Machines
• A set of software tools (libraries) for making
  efficient use of a cluster (networked) of
  computers
• Presents the developer with ability to address
  networked computers as a single virtual machine
  in order to execute computational tasks
• Heterogeneous architecture not required
• (But requires more care in setup and makefile
  (aimk) configuration)

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• Categories of operations supported
• Process Management and Control
• Message Packing and Sending
• Message Unpacking and Receiving
• Message Buffer Management
• Task Signaling
• Information and Utility Functions
• Group Operations

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• Process Management and Control
• pvm_spawn
• pvm_kill
• pvm_exit
• pvm_addhosts
• pvm_delhosts
• pvm_halt
• Means by which processes are created, assigned to
  hosts, exited, and killed
• Hosts may be added or deleted from PVM at runtime
• PVM execution stopped by pvm_halt

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• Message Packing, Sending, Unpacking, Receiving,
  and Buffer Management
• May use XDR when passing between hosts with
  incompatible formats
• May also use Raw data to send in format native to
  sending machine
• Sender does not wait for acknowledgment
• Message buffered at receiving end until received
• PVM reliably delivers messages (if destination
  exists)
• Message order from each sender to each receiver
  is preserved
• PVM Interface hides socket programming details

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Simplified Architecture of a PVM Program
Data
A
B
Data
Pack routines
Send buffer
Pack routines
Send buffer
TCP Sockets
PVM Send routines
Data
PVM Send routines
Data
PVM unpack routines
Receive buffer
PVM unpack routines
Receive buffer
PVM Receive routines
PVM Receive routines
TCP Sockets
TCP Sockets
PVMD
List of managed tasks Pvm task id 1 Pvm task id
2 Pvm task id 3
PVMD
List of managed tasks Pvm task id 100 Pvm task id
102 Pvm task id 103
UDP Sockets