blacs_set
blacs_set
Sets values that BLACS use for internal defaults.
Syntax
call blacs_set
(
icontxt
,
what
,
val
)
Input Parameters
- icontxt
- INTEGER. For values ofwhatthat are tied to a particular context, this parameter is the integer handle indicating the context. Otherwise, ignored.
- what
- INTEGER. Indicates what BLACS internal(s) should be set. Present values are:
- 1 = Set the BLACS message ID range
- 11 = Number of rings for multiring broadcast topology to use
- 12 = Number of branches for general tree broadcast topology to use
- 13 = Number of rings for multiring combine topology to use
- 14 = Number of branches for general tree combine topology to use
- 15 = Force topologies to be repeatable or not
- 16 = Force topologies to be heterogenous coherent or not
- val
- INTEGER. Array of dimension (*). Indicates the value(s) the internals should be set to. The specific meanings depend onwhatvalues, as discussed in Description below.
Description
This routine sets the BLACS internal defaults depending on
what
values:- what= 1
- Setting the BLACS message ID range.If you wish to mix the BLACS with other message-passing packages, restrict the BLACS to a certain message ID range not to be used by the non-BLACS routines. The message ID range must be set before the first call toblacs_gridinitorblacs_gridmap. Subsequent calls will have no effect. Because the message ID range is not tied to a particular context, the parametericontxtis ignored, andvalis defined as:VAL (input)array of dimension (2)INTEGERVAL(1): The smallest message ID (also called message type or message tag) the BLACS should use.VAL(2): The largest message ID (also called message type or message tag) the BLACS should use.
- what= 11
- Set number of rings forTOP = 'M'(multiring broadcast).This quantity is tied to a context, soicontxtis used, andvalis defined as:VAL (input)array of dimension (1)INTEGERVAL(1): The number of rings for multiring topology to use.
- what= 12
- Set number of branches forTOP = 'T'(general tree broadcast). This quantity is tied to a context, soicontxtis used, andvalis defined as:VAL (input)array of dimension (1)INTEGERVAL(1): The number of branches for general tree topology to use.
- what= 13
- Set number of rings forTOP = 'M'(multiring combine).This quantity is tied to a context, soicontxtis used, andvalis defined as:VAL (input)array of dimension (1)INTEGERVAL(1): The number of rings for multiring topology to use.
- what= 14
- Set number of branches forTOP = 'T'(general tree gather). This quantity is tied to a context, soicontxtis used, andvalis defined as:VAL (input)array of dimension (1)INTEGERVAL(1): The number of branches for general tree topology to use.
- what= 15
- Force topologies to be repeatable or not (see Repeatability and Coherence for more information about repeatability).VAL (input)array of dimension (1)INTEGER
- VAL(1) = 0(default)
- Topologies are not required to be repeatable.
- VAL(1)≠0
- All used topologies are required to be repeatable, which might degrade performance.
- what= 16
- Force topologies to be heterogenous coherent or not (see Repeatability and Coherence for more information about coherence).VAL (input)array of dimension (1)INTEGER
- VAL(1) = 0(default)
- Topologies are not required to be heterogenous coherent.
- VAL(1)≠0
- All used topologies are required to be heterogenous coherent, which might degrade performance.