st: MP running no faster than IC

[Ted Player <ted.player.660@gmail.com>]

Short version:  Stata MP 12-core isn't running my code any faster than
it did when I used Stata IC, and I can't figure out why.

Detailed version:  I am running Windows 7 Pro SP1 64-bit on a
quad-core machine.  I have purchased two Stata licenses.  I purchased
Intercooled when version 12 was released.  I recently purchased MP-12
core to make my Stata code run faster.  (I realize I only have four
cores so the 12 core is overkill; I want the flexibility to use
Amazon's EC2, so I purchased the 12 core version.)  Both flavors of
Stata are version 12.

Unfortunately, I am finding that MP does not run any faster than IC.
Indeed, in all my tests MP is a little slower.  To document the issue,
I did a fresh install of Stata Intercooled and then I ran benchmark.do
(below).  I ran it three times, and the average run time was 18.4
seconds.  Then I uninstalled Stata completely, installed Stata MP-12
core, and ran benchmark.do again.   I ran it three times, and the
average was 19.6 seconds.  I'm disappointed that MP isn't running
faster.

The benchmark program shown below performs a bootstrap of regression.
According to the Stata/MP Performance Report
(http://www.stata.com/statamp/report.pdf), replication-based commands
such as bootstrap were not benchmarked for the report because "these
commands run another target command repeatedly, and to the extent the
target command's performance is improved for a particular problem
size, a similar improvement will be obtained when it is run
repeatedly" (p. 7).  In the benchmark program below, the target
command is regression (which the report shows to be markedly improved
for MP).  The part of the Stata/MP Performance Report I have quoted
here seems to suggest I should expect a performance improvement in my
setup when using bootstrap.

Stata makes positively *glowing* claims about MP (e.g.,
http://www.stata.com/stata12/stata-mp), but I have yet to find any
improvement whatsoever.

I have done a creturn list to verify that I have Stata/MP installed
correctly.  The relevant parts of the creturn list are show below:

                  c(MP) = 1
          c(processors) = 4                    (Stata/MP, set processors)
      c(processors_lic) = 12
     c(processors_mach) = 4
      c(processors_max) = 4
                  c(os) = "Windows"
               c(osdtl) = "64-bit"
        c(machine_type) = "PC (64-bit x86-64)"


I should mention that when I look at the CPU usage with Windows Task
Manager, it stays at 25% while benchmark.do is running MP-12 core.
Also, I should mention that under the MP-12 core install, I have tried
"set processors 1", and I get practically the same performance that I
get from "set processors 4".  It seems to me that MP isn't using the
extra cores.

Can anyone explain to me why I'm not getting any better performance
from MP-12 core than I'm getting from IC?


benchmark.do
----------------------------------------------------------------------------------------------
clear all
sysuse auto
timer on 1
bootstrap, nodots reps(5000) seed(1): regress mpg weight gear foreign
timer off 1
quietly timer list
local elapsed = r(t1)
display "This benchmark process required ... `elapsed' ... seconds"
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