GETNTYPE (2)
getnodeid, getnodetype, getorigin, getncomp, getnotb,
getnall, getntype - Get information on LAM nodes.
SYNOPSIS
#include <net.h>
int getnodeid ();
int getnodetype ();
int getorigin ();
int getnall ();
int getncomp ();
int getnjones ();
int getnotb ();
int getntype (int nodetype, int typemask);
FORTRAN SYNOPSIS
integer function IGNDID ()
integer function IGNDTP ()
integer function IGORGN ()
integer function IGNALL ()
integer function IGNCMP ()
integer function IGNJON ()
integer function IGNOTB ()
integer function IGNTP (nodetype, typemask)
integer nodetype, typemask
DESCRIPTION
These functions return node information obtained from the local route
daemon, a modular component of the LAM daemon, regarding the currently
running LAM network.
A node is defined by its identifier, an arbitrary 32 bit value,
and its type, a combination of flags describing the capabilities of
the node.
These flags (see CONSTANTS(5) and/or <net.h>) are:
NT_ITB
node running LAM natively
NT_CAST
node multicast, a group of nodes
NT_WASTE
node not part of main computing group
NT_DISK
NT_TUBE
node has a video display unit
NT_JONES
node is a neighbour of the local node
NT_BOOT
node is booted by the local node
getnodeid()
returns the local node identifier.
getnodetype()
returns the local node type.
getorigin()
returns the origin node identifier, from which LAM was booted.
getncomp()
returns the number of nodes marked for the "main" computation.
A typical application will use most (maybe all) of the nodes in
a parallel machine to compute portions of decomposed data.
Programmers frequently need to know the number of these "compute" nodes.
Other nodes may be present in the multicomputer to handle peripherals
or sequential portions of an application.
getnotb()
returns the total number of OTB nodes.
getnall()
returns the total number of nodes in the system.
getnjones()
returns the caller's number of neighbour (directly connected) nodes.
getntype()
is a general function that is used to determine the number of nodes
whose node types have certain bits set to certain values.
This is a flexible tool which allows the user to obtain very specific
information about the capabilities of nodes in the system.
You may need more detailed information on the number and types of nodes
in the system than provided by the convenience functions.
You may, for example, want to know the number of computing nodes with
attached video displays.
The
getntype()
function is used for this purpose.
Node types are interpreted as bit fields, and each node type
has a different bit set.
A bitmask having all bits set, NT_ALL, is also available.
Note that NT_ALL does not include NT_JONES nor NT_BOOT since these
node characteristics are not inherent to the nodes, but depend on the
node from which the query is made.
The node types are thus:
1.3i 2.3i
Nodetype Value Bitmask
NT_ITB 1 ...00000001
NT_CAST 2 ...00000010
NT_WASTE 4 ...00000100
NT_DISK 8 ...00001000
NT_TUBE 16 ...00010000
NT_ALL 31 ...00011111
NT_JONES 32 ...00100000
NT_BOOT 64 ...01000000
The
typemask
argument to
getntype()
is used to specify which bits are of interest.
These are set to 1, all others are set to 0.
The
nodetype
argument is used to specify what values these bits should take.
getntype()
then compares the relevant bits (as specified by
typemask )
in the node type of each node in the system, to
see if they have the appropriate value (as specified by
nodetype ).
To learn the number of nodes that have video capabilities,
the bits of interest are NT_WASTE and NT_TUBE, thus
typemask
is 20.
NT_WASTE must be 0 and NT_TUBE must be 1, which combined gives
nodetype
as 16.
The complete call to
getntype()
is:
nnodes = getntype(NT_TUBE, NT_TUBE | NT_WASTE);
To learn the number of compute nodes that have an attached video
display, but no other capabilities, all bits must be considered and
all bits except NT_TUBE must be clear (0).
The complete function call is:
nnodes = getntype(NT_TUBE, NT_ALL);
C RETURN VALUE
getnodeid()
and
getorigin()
both return node identifiers.
NOTNODEID (defined in <net.h>) is returned if an error occurred.
Likewise,
getnodetype()
returns a valid node type or NOTNODETYPE in the case of error.
The return values upon successful completion for the remaining
functions are described above; they return -1 if an error occurs.
In all cases of error, the global error variable
errno
is set to indicate the error.
FORTRAN RETURN VALUE
IGNDID()
and
IGORGN()
both return node identifiers.
NOTNODEID (see CONSTANTS(5)) is returned if an error occurred.
Likewise,
IGNDTP()
returns a valid node type or NOTNODETYPE in the case of error.
The return values upon successful completion for the remaining
functions are described above; they return -1 if an error occurs.
SEE ALSO
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