Parallel code runs slower!
Can you provide a little more information. What operating system are you using? Have you monitored the CPU and memory utilizations of the processes? Do you have enough physical memory; e.g., are you paging? How big are the matrices that you are processing; e.g., str(tTA) and object.size(tTA). This is the type of information that would be required to make an informed guess at what is happening. On Wed, Nov 10, 2010 at 9:07 AM, Santosh Srinivas
<santosh.srinivas at gmail.com> wrote:
My parallel code is running slower than my non-parallel code! Can someone
pls advise what am I doing wrong here?
t and tTA are simple matrices of equal dimensions.
#NON PARALLEL CODE
nCols=ncol(t)
nRows=nrow(t)
tTA = matrix(nrow=nRows,ncol=nCols)
require(TTR)
system.time(
for (i in 1:nCols) {
? ? ? ?x = t[,i]
? ? ? ?xROC = ROC(x)
? ? ? ?tTA[,i]=xROC
? ? ? ?}
)
? user ?system elapsed
?123.24 ? ?0.07 ?123.47
# PARALLEL CODE
nCols=ncol(t)
nRows=nrow(t)
tTA = matrix(nrow=nRows,ncol=nCols)
require(doSMP)
workers <- startWorkers(4) # My computer has 4 cores
registerDoSMP(workers)
system.time(
foreach (i=1:nCols) %dopar%{
? ? ? ?x = t[,i]
? ? ? ?xROC = ROC(x)
? ? ? ?tTA[,i]=xROC
? ? ? ?}
)
# stop workers
stopWorkers(workers)
It is taking ages!
Thanks,
S
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