Evendist - Revision history

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2019-04-15T15:44:38Z

5 revisions imported

Polas at 14:20, 15 April 2013

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Polas at 18:19, 13 January 2013

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Polas at 17:51, 12 January 2013

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Polas: /* Example */

2013-01-12T17:35:07Z

‎Example

Polas: Created page with '== Syntax == evendist[] == Semantics == Will distribute data blocks evenly amongst the processes. If there are too few processes then the blocks will wrap around, if there are…'

2010-01-10T21:26:29Z

Created page with '== Syntax == evendist[] == Semantics == Will distribute data blocks evenly amongst the processes. If there are too few processes then the blocks will wrap around, if there are…'

New page

== Syntax ==

evendist[]

== Semantics ==

Will distribute data blocks evenly amongst the processes. If there are too few processes then the blocks will wrap around, if there are too few blocks then not all processes will receive a block. The figure below illustrates even distribution of 10 blocks of data over 4 processes.

<center>[[Image:evendist.jpg|Even distribution of 10 blocks of data over 4 processors using type oriented programming]]</center>

== Example ==

var a:array[Int,16,16] :: allocated[row[] :: horizontal[4] :: single[evendist[]]];
var b:array[Int,16,16] :: allocated[row[] :: vertical[4] :: single[evendist[]]];
var e:array[Int,16,16] :: allocated[row[] :: single[on[1]]];
var p;
par p from 0 to 3
{
var q:=(((b#p)#2)#3);
var r:=(((a#p)#2)#3);
var s:=((((b :: horizontal[])#p)#2)#3);
};
a:=e;

In this example (which involves 4 processors) there are three [[array|arrays]] declared, ''a'', ''b'' and ''e''. Array ''a'' is [[horizontal|horizontally]] partitioned into 4 blocks, evenly distributed amongst the processors, whilst ''\emph b'' is [[vertical|vertically]] partitioned into 4 blocks and also evenly distributed amongst the processors. Array ''e'' is located on processor 1 only. All arrays are allocated [[row]] major. In the [[par]] loop, variables ''q'', ''r'' and ''s'' are declared and assigned to be values at specific points in a processor's block. Because ''b'' is partitioned [[vertical|vertically]] and ''a'' [[horizontal|horizontally]], variable ''q'' is the value at ''b's'' block memory location 11, whilst ''r'' is the value at ''a's'' block memory location 35. On line 9, variable ''s'' is the value at ''b's'' block memory location 50 because, just for this expression, the programmer has used the [[horizontal]] type to take a horizontal view of the distributed array. It should be noted that in line 9, it is just the view of data that is changed, the underlying data allocation is not modified.
In line 11 the assignment ''a:=e'' results in a scatter as per the definition of its declared type.

[[Category:Type Library]]
[[Category:Composite Types]]
[[Category:Distribution Types]]

← Older revision	Revision as of 15:44, 15 April 2019
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 == Example ==
-  var a:array[Int,16,16] :: allocated[row[] :: horizontal[4] :: single[evendist[]]];
+  function void main() {
- var b:array[Int,16,16] :: allocated[row[] :: vertical[4] :: single[evendist[]]];
+    var a:array[Int,16,16] :: allocated[row[] :: horizontal[4] :: single[evendist[]]];
- var e:array[Int,16,16] :: allocated[row[] :: single[on[1]]];
+    var b:array[Int,16,16] :: allocated[row[] :: vertical[4] :: single[evendist[]]];
- var p;
+    var e:array[Int,16,16] :: allocated[row[] :: single[on[1]]];
- par p from 0 to 3
+    var p;
+    par p from 0 to 3 {
-    var q:=b[p][2][3];
+       var q:=b[p][2][3];
-    var r:=a[p][2][3];
+       var r:=a[p][2][3];
-    var s:=b :: horizontal[][p][2][3];
+       var s:=b :: horizontal[][p][2][3];
   };
 In this example (which involves 4 processors) there are three [[array|arrays]] declared, ''a'', ''b'' and ''e''. Array ''a'' is [[horizontal|horizontally]] partitioned into 4 blocks, evenly distributed amongst the processors, whilst ''\emph b'' is [[vertical|vertically]] partitioned into 4 blocks and also evenly distributed amongst the processors. Array ''e'' is located on processor 1 only. All arrays are allocated [[row]] major. In the [[par]] loop, variables ''q'', ''r'' and ''s'' are declared and assigned to be values at specific points in a processor's block. Because ''b'' is partitioned [[vertical|vertically]] and ''a'' [[horizontal|horizontally]], variable ''q'' is the value at ''b's'' block memory location 11, whilst ''r'' is the value at ''a's'' block memory location 35. On line 9, variable ''s'' is the value at ''b's'' block memory location 50 because, just for this expression, the programmer has used the [[horizontal]] type to take a horizontal view of the distributed array. It should be noted that in line 9, it is just the view of data that is changed, the underlying data allocation is not modified.

@@ Line 27: / Line 27: @@
 In line 11 the assignment ''a:=e'' results in a scatter as per the definition of its declared type.
 [[Category:Type Library]]
 [[Category:Compound Types]]
 [[Category:Distribution Types]]