MPICH2 : Introduction to MPI_Init

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MPICH2 Introduction to MPI_Init

• Oct 5, 2005
• Sogang University
• Distributed Computing Communication Laboratory
• Eunseok, Kim

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Outline

• Internal routine naming
• Flow chart of MPI_Init ()
• Global Object
• Series of functions
• Conclusion

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Internal routine name

• MPI
• MPI implementation
• MPIR
• Routines used only within the MPI implementation
• Outside of the ADI
• MPID
• Routines either defined in the ADI or used within
  the ADI
• MPIU
• Routines that are defined in the util directory
  and may be used by either the ADI or the
  implementation of the MPI routines

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Concept of Initialization

• Lazy initialization
• Each module initialize itself
• Reduce
• Executable size
• Link time
• Enabled by Weak symbol option

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MPI_Init
MPI_Init(int argc, )
MPIR_Init_thread( int argc..)
MPIR_Err_init( int argc..)
MPIR_Wtime_init( int argc..)
MPIR_Datatype_init( int argc..)
MPIR_Nest_init( int argc..)
MPID_Init ( int argc..)
MPIDI_CH3_Init( int argc..)
End of MPI_Init
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Global Object

• MPIR_Process
• MPIDI_Process
• MPIDI_CH3_Process
• Etc
• Each module has its own global variable
• Init finalized within the module

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MPIR_Process

• Comm
• Comm_world
• Comm_self
• Comm_parent (spawn)
• Group
• Remote / local
• Comm_kind
• Intra / inter
• VCRT (Virtual Connection Reference Table)
• Thread
• Condition variables
• Attribute
• Attribute variable
• Attribute function

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MPIDI_Process

• Receive queue
• Posted
• Unexpected
• Process group id rank
• Condition variable

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MPIDI_CH3I_Process

• Parent port number
• Accept queue
• Condition variable

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MPI_Init()

• Declare nest level value
• Ex) MPID_MPI_INIT_STATE_DECL(MPID_STATE_MPI_INIT)
• Init critical section
• Thread mutex creation
• Call MPIR_Init_thread

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MPIR_Init_thread()

• Address alignment issues
• Ex) HAVE_WINDOWNS_H, _WIN64
• Setup MPIR_Process object
• attrs
• Init comm (null)
• Call all MPID_Init type functions
• Ex) MPIR_Err_init(), MPIR_Datatype_init()
• Determine Several policy
• Ex) allowing the device to select an alternative
  function for some function
• Call MPID_Init (Ch3)

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MPID_Init

• Init receive queues
• Set processor name and other configurations
• By system call and environmental variable
• Call MPIDI_CH3_Init
• Assign Process group id rank to MPIDI_Process
• Cf) rank in comm_world
• Init MPI_COMM_(WORLD / SELF) object
• Creating VCRT
• Get parent or parent port
• Determine who my parent is
• Others or no parent
• Synchronization through MPIR_Bcast

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MPIDI_CH3_Init

• PMI_Init
• Port
• Host name
• Fd (socket)
• PMI_Get_(rank/id)
• Pg_rank
• Pg_id
• Init and create Process group
• Init pgs vct and send-queue

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Summary

• Modular architecture
• Provides independence
• Local init / finalization
• Developer can implement an algorithm within a
  specific module
• Obey the interfaces
• And link
• However
• Too complicated
• Too deep reference link
• Scattered source
• More precise analysis can be possible
• After analyzing coll and ptp, etc