amd64 slower than i386 on identical AMD 64 system?

[Sean McNeil]

On Thu, 2006-03-16 at 13:21 -0500, Mike Jakubik wrote:
> JoaoBR wrote:
> > I never had any kind of problem with any system with <= 2Gb of Ram
> >   
> 
> Ok then, how abut this puppy? It's a dual dual-core opteron server, with 
> 2 GB ram, and it's running perfectly. The most likely cause of your 
> problem is hw, if you have problems with 2GB of ram on a normal kernel.
> 
> ---
> CPU: Dual Core AMD Opteron(tm) Processor 265 (1808.34-MHz 686-class CPU)
>   Origin = "AuthenticAMD"  Id = 0x20f12  Stepping = 2
>   
> Features=0x178bfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CLFLUSH,MMX,FXSR,SSE,SSE2,HTT>
>   Hyperthreading: 2 logical CPUs
>   AMD Features=0xe0500000<NX,AMIE,LM,DSP,3DNow!>
> real memory  = 2146500608 (2047 MB)
> avail memory = 2099249152 (2002 MB)
> ACPI APIC Table: <PTLTD          APIC  >
> FreeBSD/SMP: Multiprocessor System Detected: 4 CPUs
>  cpu0 (BSP): APIC ID:  0
>  cpu1 (AP): APIC ID:  1
>  cpu2 (AP): APIC ID:  2
>  cpu3 (AP): APIC ID:  3

This is not on his list either.  I have an Athlon 64 X2 3800 with 2GB of
RAM that works perfectly, but it doesn't fall into his failure category.

Wonder if there is some sort of memory pairing issue. To get >2GB and
<4GB I'd think you have to have 2 1GB sticks and 2 512MB sticks or
something like that.

Anytime I've had issues, someone has told me it is my memory - and they
were right.  Running SMP vs. UP vs. amd64 vs. x86 all use memory
differently.