It's sad, but not an impossible result with synchronization overhead
(though I wouldn't have guessed it would be that bad) -- can you try
it on a more reasonable benchmark?
Also, that advice might be somewhat out of date -- why not use the
tools provided in
library(parallel)
available for recent versions of R?
Michael
On Thu, Jul 26, 2012 at 8:00 AM, deep123 <deps_...@yahoo.co.in> wrote:
> Hello all,
> My problem is similar to Sergey's.
> I could not try what Mario suggested, since doMPI is not available for
> windows.
>
> I have tried the Cedrick's commands, i.e.
> cl.tmp = makeCluster(rep("localhost",2), type="SOCK")
> registerDoSNOW(cl.tmp)
>
> but this is instead increasing the time taken. For Sergy's set of commands,
> i get,
>> x <- numeric(10000)
>> system.time(for(i in 1:10000) x[i] <- sqrt(i))
> user system elapsed
> 0.03 0.00 0.03
>> system.time(system.time(x <- foreach(i=1:10000, .combine="c") %do%
>> sqrt(i)))
> user system elapsed
> 4.71 0.00 4.71
>> system.time(system.time(x <- foreach(i=1:10000, .combine="c") %dopar%
>> sqrt(i)))
> user system elapsed
> 7.35 1.07 127.06
>
> i.e. %dopar% is taking longer than %do%
>
> Please guide me.
>
>
>
> --
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