Just a thought: Wouldn't it make more sense to compare the "elapsed"
times, which show that both machines are more or less equally fast
(with a slide edge for the newer i5)?
I suspect that there is a change in the way "user" time is reported,
which probably adds up running times of four hyperthreads running on
two cores for the i5 CPU vs. only two threads on two cores for the
Core 2 Duo. If I'm not mistaken about the i5 architecture, this is
not surprising: there are 4 threads, but they have to share 2 cores
and don't seem to be able to run the FP instructions in parallel on a
single core; so they're running at half speed only.
Thanks for the benchmark, by the way. It's good to know I'm not
missing out on R performance with my good old 2008 MacBook Pro. :-)
Cheers,
Stefan
On 8 May 2010, at 20:53, Gardar Johannesson wrote:
###########################################
## Results from new macbook pro (Core i5 @ 2.4Ghz)
set.seed(1)
A <- matrix(rnorm(2000*2000),2000,2000)
system.time(B <- crossprod(A))
user system elapsed
2.500 0.058 0.816
system.time(B <- crossprod(A))
user system elapsed
2.502 0.050 0.814
system.time(solve(B))
user system elapsed
7.208 0.265 2.740
system.time(solve(B))
user system elapsed
7.121 0.264 2.666
system.time({a <- rep(1.0,100); for(i in 1:1e6) a <- 1.0*a+0.0})
user system elapsed
2.964 0.602 3.528
system.time({a <- rep(1.0,100); for(i in 1:1e6) a <- 1.0*a+0.0})
user system elapsed
3.040 0.732 3.732
###################################################
## Results from old macbook pro (Core 2 Duo @ 2.2GHz)
set.seed(1)
A <- matrix(rnorm(2000*2000),2000,2000)
system.time(B <- crossprod(A))
user system elapsed
1.429 0.073 0.800
system.time(B <- crossprod(A))
user system elapsed
1.429 0.064 0.874
system.time(solve(B))
user system elapsed
4.532 0.285 2.860
system.time(solve(B))
user system elapsed
4.521 0.281 2.834
system.time({a <- rep(1.0,100); for(i in 1:1e6) a <- 1.0*a+0.0})
user system elapsed
3.501 0.764 4.215
system.time({a <- rep(1.0,100); for(i in 1:1e6) a <- 1.0*a+0.0})
user system elapsed
3.459 0.702 4.113
sessionInfo()
R version 2.11.0 (2010-04-22)
i386-apple-darwin9.8.0
locale:
[1] en_US.UTF-8/en_US.UTF-8/C/C/en_US.UTF-8/en_US.UTF-8
attached base packages:
[1] stats graphics grDevices utils datasets methods base
###################################################
## Results from new macbook pro (Core i5 @ 2.4Ghz)
## Linking against Goto2 BLAS (vs vecLib)
set.seed(1)
A <- matrix(rnorm(2000*2000),2000,2000)
system.time(B <- crossprod(A))
user system elapsed
2.348 0.124 0.635
system.time(B <- crossprod(A))
user system elapsed
2.342 0.110 0.622
system.time(solve(B))
user system elapsed
6.634 0.327 2.158
system.time(solve(B))
user system elapsed
6.697 0.348 2.034
system.time({a <- rep(1.0,100); for(i in 1:1e6) a <- 1.0*a+0.0})
user system elapsed
2.577 0.548 2.885
system.time({a <- rep(1.0,100); for(i in 1:1e6) a <- 1.0*a+0.0})
user system elapsed
2.411 0.478 2.859
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