[K12OSN] 64 bit ltsp vs. virtualization

James P. Kinney III jkinney at localnetsolutions.com
Tue Jun 24 12:01:06 UTC 2008

On Tue, 2008-06-24 at 07:05 -0400, Julius Szelagiewicz wrote:

> 	I have one application - DB/C language interpreter, that all the
> users run, that shows eightfold increase in speed between 32bit and 64bit
> versions.
That is very odd. 64-bit does not provide speed. Speed is handled by the
clock rating of the core. The bit count determines the size of the
addressing area that can be directly accessed for RAM. Internally, the
cpu's don't have enough cache to be affected by the bit size. 
An 8-fold speed increase is tremendous. If this is being run on a
multi-core machine, the speed increase may be more related to better
threading control in the 64-bit system than the 32-bit (assuming the
same machine). The 64/32 bit system like Opterons and Xeons are more
efficient in 64-bit mode as it's a single clock tick to fill buffers but
it takes an extra tick every 2 fills for 32-bit mode (has to store 2
addresses per fill in 32 bit vs. 1 per 64 - cache writes take a tick).
James P. Kinney III          
CEO & Director of Engineering 
Local Net Solutions,LLC                           

GPG ID: 829C6CA7 James P. Kinney III (M.S. Physics)
<jkinney at localnetsolutions.com>
Fingerprint = 3C9E 6366 54FC A3FE BA4D 0659 6190 ADC3 829C 6CA7

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