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Topic Title: Differences between Phenom II X4 and Opeteron 8-core
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Created On: 06/08/2010 06:50 PM
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 06/08/2010 06:50 PM
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arshadnoor1
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Hi,

We develop a cryptographic application on desktops outfitted with Phenom II X4 B95 processors, 64-bit Centos 5.4 and Java. The machine also has 8GB of PC2 8500 Mhz memory and a 500GB 7200RPM SATA HDD. It also has an ATI HD graphics card with 512MB memory on it. The application is an Encryption and Key Management (EKM) system that provides cryptographic web-services and manages keys on the back-end.

We have a benchmark test of 1000 encryption and decryption web-service transactions that we have clocked on this desktop, and it executes these 2000 transactions in an average of 30 seconds in its default configuration (no tuning).

We recently got a 1U rack-mounted server from a large vendor with an 8-core Opteron, 8GB of PC3 13333 Mhz memory and 2 500GB HDDs of 7200RPM - no RAID.

We expected this new machine to fly with our benchmark given its 8-cores, faster memory, etc. Yet, this server took a staggering 206 - 227 seconds to complete!! The boot-up messages indicate nothing wrong with the configuration. But depsite tuning, we're unable to lower this time below 206 seconds. We even turned of test output to avoid using the graphics chip (since the desktop had an advantage over the server with its HD card). But, the time would budge below 206 seconds.

Yet a quad-core Opteron server from another manufacturer was able to deliver the benchmark in 59 seconds. Should not the doubling of cores have improved performance at least by some percentage?

Questions for the forum:

1) Could we be doing something wrong with the new 8-core server box?
2) Is the Phenom II radically different from the 8-core Opteron in its ability to perform cryptographic operations, and does it have a distinct advantage over Opteron?

Thanks in advance for hints and/or advice.
 06/14/2010 12:34 PM
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MU_Engineer
Dr. Mu

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There are a few reasons why your 8-core server could be slower:

1. Your benchmark may not be well-threaded and the 3.0 GHz B95 has a large clock speed advantage over any 8-core Opterons (which run at 2.0-2.4 GHz). However, you'd expect times of more like 45 seconds if that was the case.

2. The power management is not set up properly and the 8-core units are running at their idle speed of 800 MHz instead of at their full 2.0-2.4 GHz speed. That would suggest a run time somewhere in the 120-second range instead of >200 seconds.

3. You are having software issues with the OS the 8-core machine is running on that results in you using a software stack that is by default far a lot slower than you did with the Phenom II.

The 8-core units are basically two of the Phenom IIs sitting next to each other underneath the heatspreader of the CPU. They should perform roughly similarly clock-for-clock and core-for-core.

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 06/14/2010 12:40 PM
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I3r0k3n7FEET
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server chips and desktop chips are VERY different. despite the problems you are having the above post has given many reasons why it could be. in regards to architecture the opteron vs phenom 2.. very very different..

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 06/14/2010 12:51 PM
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MU_Engineer
Dr. Mu

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Originally posted by: Death9000

server chips and desktop chips are VERY different. despite the problems you are having the above post has given many reasons why it could be. in regards to architecture the opteron vs phenom 2.. very very different..


The platform architecture of the G34 Opterons is considerably different from the Phenom IIs, but the microarchitecture is identical. The silicon dies used in the "Magny-Cours" G34 chips are just about identical to the Phenom II X6 "Thuban," for example (the 8-core chips contain two six-core dies with two cores on each die disabled.)

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 06/14/2010 06:29 PM
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I3r0k3n7FEET
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it would appear you are right :/ just shows you cant alway believe what you read. lol

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 07/26/2010 06:58 AM
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jacklinjones
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I also have the problem of slower performance of 8-core server. But it was because of power management and when I found out the problem, I made changesd to the power management and made it proper. I also check out my operating system where I am using it but there is no problem.
 08/24/2010 12:35 AM
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arshadnoor1
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So, are you saying that the machine is now operating at full-speed without any issues? Where did you configure the power configuration? Thanks.
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