It runs more than twice as slowly using 8 core than using a single core
in inverting large matrix. Tested on 8 core Windows XP 64 machine. 

 

 

> n = 1000

> n.simu = 100 

> func1 = function()

+ {

+   x = rnorm(n*n)

+   dim(x)=c(n,n) 

+  y = solve(x)

+ }

> 

> setMKLthreads(1)

> system.time(for(i in 1:n.simu) func1())

   user  system elapsed 

  69.48    2.42   71.91 

> 

> setMKLthreads(8)

> system.time(for(i in 1:n.simu) func1())

   user  system elapsed 

 179.06   17.90   41.70

 

Jason Liao


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