Template:ElementTypeCommunication - Revision history

Polas: 5 revisions imported

2019-04-15T15:44:30Z

5 revisions imported

Polas: /* Communication Example */

2016-10-18T12:51:17Z

‎Communication Example

Polas at 12:50, 18 October 2016

2016-10-18T12:50:42Z

Polas at 16:20, 12 January 2013

2013-01-12T16:20:34Z

Polas at 00:20, 4 January 2010

2010-01-04T00:20:12Z

Polas: Created page with 'When a variable is assigned to another, depending on where each variable is allocated to, there may be communication required to achieve this assignment. Table \ref{tab:eltypecom…'

2010-01-04T00:09:41Z

Created page with 'When a variable is assigned to another, depending on where each variable is allocated to, there may be communication required to achieve this assignment. Table \ref{tab:eltypecom…'

New page

When a variable is assigned to another, depending on where each variable is allocated to, there may be communication required to achieve this assignment. Table \ref{tab:eltypecomm} details the communication rules in the assignment \emph{assignmed variable := assigning variable}. If the communication is issued from MPMD programming style then this will be one sided. The default communication listed here is guaranteed to be safe, which may result in a small performance hit.

{| border="1" cellspacing="0" cellpadding="5" align="center"
! Assigned Variable
! Assigning Variable
! Semantics
|-
| multiple[]
| multiple[]
| local assignment
|-
| single[on[i]]
| multiple[]
| local assignment on process i
|-
| multiple[]
| single[on[i]]
| broadcast from process i
|-
| single[i]
| single[i]
| local assignment where i==i
|-
| single[i]
| single[j]
| communication from j to i where i!=j
|}

==== Communication Example ====

var a:Int;
var b:Int :: allocated[single[on[2]]];
var p;
par p from 0 to 3
{
if (p==2) b:=p;
a:=b;
};

This code will result in a onesided broadcast (due to being written MPMD style in ''par'' loop) where process 2 will broadcast its value of ''b'' to all other processes who will write it into ''a''. As already noted, in absence of allocation information the default of allocating to all processes is used. In this example the variable ''a'' can be assumed to additionally have the type ''allocated[multiple]''.

← Older revision		Revision as of 12:51, 18 October 2016
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−	This code will result in each process reading the value of ''b'' from process 2 and then writing this into ''a''. As already noted, in absence of allocation information the default of allocating to all processes is used. In this example the variable ''a'' can be assumed to additionally have the type ''allocated[multiple]''.	+	This code will result in each process reading the value of ''b'' from process 2 and then writing this into ''a''. As already noted, in absence of allocation information the default of allocating to all processes is used. In this example the variable ''a'' can be assumed to additionally have the type ''allocated[multiple]''. Note that communication groups are the same as multiple in this context and share the same semantics. All variables marked multiple are private to their containing process.

← Older revision	Revision as of 15:44, 15 April 2019
(No difference)

@@ Line 13: / Line 13: @@
 | single[on[i]]
 | multiple[]
-| communication onto process i
+| individual processes write values to process i
 |-
 | multiple[]
 | single[on[i]]
-| broadcast from process i
+| individual processes read values from process i
 |-
 | single[on[i]]
@@ Line 36: / Line 36: @@
      if (p==2) b:=p;
      a:=b;
   };
-This code will result in a onesided broadcast (due to no further type information present, this is  the default behaviour of element types) where process 2 will broadcast its value of ''b'' to all other processes who will write it into ''a''. As already noted, in absence of allocation information the default of allocating to all processes is used. In this example the variable ''a'' can be assumed to additionally have the type ''allocated[multiple]''.
+This code will result in each process reading the value of ''b'' from process 2  and then writing this into ''a''. As already noted, in absence of allocation information the default of allocating to all processes is used. In this example the variable ''a'' can be assumed to additionally have the type ''allocated[multiple]''.

@@ Line 19: / Line 19: @@
 | broadcast from process i
 |-
-| single[i]
+| single[on[i]]
-| single[i]
+| single[on[i]]
 | local assignment where i==i
 |-
-| single[i]
+| single[on[i]]
-| single[j]
+| single[on[j]]
 | communication from j to i where i!=j
 |}