--- name: "getntype" section: "2" platform: "linux" package: "lam2-dev" version: "6.3.2-3" release: "Debian 2.2 (Potato)" platforms: ["linux"] url: "https://new.carta.tech/getntype" --- # getntype(2) Get information on LAM nodes. ## NAME getnodeid, getnodetype, getorigin, getncomp, getnotb, getnall, getntype - Get information on LAM nodes. ## SYNOPSIS ``` #include 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)](/CONSTANTS/5.md) and/or \) 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 node has a 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. ### Type Inquiries 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: ``` 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 \) 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)](/CONSTANTS/5.md)) 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 [getroute(2)](/getroute/2.md), [CONSTANTS(5)](/CONSTANTS/5.md)