Why is MySQL nearly twice as fast on Linux/AMD64 Vs. FreeBSD/AMD64?

Tue May 18 16:56:11 PDT 2004

JG wrote:

>
> Dual AMD Opteron 240's (1.4ghz)
> Tyan S2882UGNR server-class motherboard w/LSI Zero channel Raid card.
> 2 gigs PC-2700 registered ECC memory
> Seagate barracuda ATA 100 system drive
> RAID-0 Mysql drive composed of 2 15k RPM U160 SCSI Fujistu drives.

How is the memory laid out?  How many DIMMs, and are they evenly spread 
between the CPUs?