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answer // further // Benchmark - 64 bit much slower than 32 bit

• To: mathgroup at smc.vnet.net
• Subject: [mg111799] answer // further // Benchmark - 64 bit much slower than 32 bit
• From: "Scot T. Martin" <smartin at seas.harvard.edu>
• Date: Fri, 13 Aug 2010 06:58:26 -0400 (EDT)

In case any one else runs into a similar problem, I sorted out the answer 
to the slowness below. I pulled out one memory strip to drop from 8 MB to 
6 MB and, presto, performance went from slow (rating of 1.13) to ultrafast 
(rating of 5.50).

How to explain this? I believe it goes back to "following the 
manufacturer's recommendation". That is, this computer is provided in 
configurations of 6 MB or 12 MB. My IT department bought a 2 MB memory 
strip and pumped it up from 6 to 8 MB. It seems there must be some kind of 
hardware inbalancing in the memory that influences the speed of some 
calculations; details are beyond my technical level. But the problem has 
been fixed by "following the manufacturer's suggestion on memory 
configurations".



---------- Forwarded message ----------
Date: Wed, 11 Aug 2010 19:38:13 -0400 (EDT)
From: Scot T. Martin <smartin at seas.harvard.edu>
To: mathgroup at smc.vnet.net
Subject: [mg111799] further // Benchmark - 64 bit much slower than 32 bit (fwd)

This issue is more subtle than outlined in the last email because I ran 
Benchmark[] on yet another computer that also has Windows 7 64-bit and got very 
good results. Here is a full comparison --- any insights on the slow one?

**** FASTEST ****
Intel(R) Core(TM) i5 CPU  650 @3.20GHz, 8.00 GB
=== System Information ===
Machine Name:          smartin-t1500pc
System:                Microsoft Windows (64-bit)
Date:                  August 11, 2010
Mathematica Version:   7.0.0
Benchmark Result:      4.71

smartin-t1500pc
Microsoft Windows (64-bit)     18.3   1.05    0.36    0.52    1.22    1.67 0.22 
0.50    1.81    2.11    1.08     1.84     1.34     1.11     1.59 1.89


**** NEXT FASTEST ****
Intel(R) Core(TM)2 Duo CPU E8500 at 3.16 Ghz, 2.75 GB RAM
=== System Information ===
Machine Name:          martin2
System:                Microsoft Windows (32-bit)
Date:                  August 11, 2010
Mathematica Version:   7.0.0
Benchmark Result:      4.12


martin2
Microsoft Windows (32-bit)     20.9   1.20    0.59    0.83    1.25    1.89 0.44 
0.77    2.61    1.83    1.42     2.05     1.45     1.25     1.42 1.91



*** WAY TOO SLOW (new system) ***
Intel(R) Xeon(R) CPU, W3680 at 3.33 GHz, 8.00 GB install, Windows 7 professional 
64 bit
=== System Information ===
Machine Name:          profmartinoffic
System:                Microsoft Windows (64-bit)
Date:                  August 11, 2010
Mathematica Version:   7.0.0
Benchmark Result:      1.13

profmartinoffic
Microsoft Windows (64-bit)     76.2   1.87    0.33    0.39    26.10   1.83 0.23 
0.48    1.89    1.70    0.84     1.72     1.05     1.15     23.80 12.80



original email:

Folks, just installed Mathematica on new Windows 7 64-bit machine and 
Benchmark[] is much slower than on 32-bit Windows XP.
MathematicaMark7 Rating of new system is 1.13 compared to 4.12 of old system.

Any explanations for this? Details are below. Are many of Mathematica's 
routines still in 32-bit and thus slower on 64-bit
machine? Is this an issue related to Windows XP compared to Windows 7 vis-a-vis 
Mathematica?

Needless to say, new system is much better in terms of CPU, memory, etc., so 
this result is very surprising to me. I'd like to
know what I can adjust to get a blazing Benchmark!