Re: What's the best hardver for PostgreSQL 8.1?

[William Yu <wyu@xxxxxxxxxxx>]

Juan Casero wrote:
> Can you elaborate on the reasons the opteron is better than the Xeon when it 
> comes to disk io?   I have a PostgreSQL 7.4.8 box running a DSS.   One of our 

Opterons have 64-bit IOMMU -- Xeons don't. That means in 64-bit mode, 
transfers to > 4GB, the OS must allocated the memory < 4GB, DMA to that 
block and then the CPU must do extra work in copying the memory to > 
4GB. Versus on the Opteron, it's done by the IO adaptor using DMA in the 
background.