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Re: [Xen-users] 32bit vs 64bit memory usage question



Hi,

Well, I didn't ask if it was faster......

And no it is not necessarily slower, x86-64 architecture has various other improvements, in particular the number of available CPU registers.

Jamie.

----- Original Message ----- From: "Tom Miller" <madprogextrodinr@xxxxxxxxx>
To: <xen-users@xxxxxxxxxxxxxxxxxxx>
Sent: Monday, February 05, 2007 3:00 PM
Subject: Re: [Xen-users] 32bit vs 64bit memory usage question


Jamie Burns wrote:
Hello,

I recently installed a minimal 32bit version of Debian Etch, and then also installed Xen from Debian's package repository.

When Xen booted up, memory usage was just below 40MB (typical for such a debian install).

Then I decided to do the exact same install, but using the 64bit version of Debian Etch and Xen.

This time when Xen booted up, memory usage was just over 90MB - at least double that of the 32bit version.

Can anybody explain this to me? Why 64bit XEN would use double the memory?

If I try 32bit vs 64bit debian without using XEN, then memory use about 30MB with each - no doubling.

Jamie Burns.

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64 bit pointers and 64 bit memory address slots are twice as big as
corresponding 32 bit ones.   So unless you have 4 GB of memory or more,
using 64bit software is actually slower for the system, not faster.


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