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Snow Parallel R: makeCluster with more nodes than available

3 messages · Ubuntu Diego, Uwe Ligges, Dirk Eddelbuettel

Ubuntu Diego
# 
Hi all,
	I would like to know what would happen if using snow I create a cluster
of size 50, for example using makeCluster(50,type='SOCK') on a machine
with 2 Cores and run a function. Does snow run 25 and 25 functions on
each of my 2 "real" processors or it just run 50 functions in one
processor ?
Thanks.
Uwe Ligges
#
Ubuntu Diego wrote:
It will run the 50 in parallel and is not advisable to do so on a 
machine with 3 cores - a slow down due to "administrative" overhead is 
expected.

Uwe Ligges
Dirk Eddelbuettel
#
On 27 March 2009 at 13:19, Uwe Ligges wrote:
|
| Ubuntu Diego wrote:
| > Hi all,
| > 	I would like to know what would happen if using snow I create a cluster
| > of size 50, for example using makeCluster(50,type='SOCK') on a machine
| > with 2 Cores and run a function. Does snow run 25 and 25 functions on
| > each of my 2 "real" processors or it just run 50 functions in one
| > processor ?
| 
| It will run the 50 in parallel and is not advisable to do so on a 
| machine with 3 cores - a slow down due to "administrative" overhead is 
| expected.

Morevoer those 50 session have to share the existing memory allocation --
which is hardly likely to be large enough.

Dirk
 
| Uwe Ligges
| 
| 
| 
| > Thanks.
| > 
| > ______________________________________________
| > R-help at r-project.org mailing list
| > https://stat.ethz.ch/mailman/listinfo/r-help
| > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
| > and provide commented, minimal, self-contained, reproducible code.
| 
| ______________________________________________
| R-help at r-project.org mailing list
| https://stat.ethz.ch/mailman/listinfo/r-help
| PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
| and provide commented, minimal, self-contained, reproducible code.