Jim C. Nasby wrote:
On Tue, Feb 01, 2005 at 07:35:35AM +0100, Cosimo Streppone wrote:

You might look at Opteron's, which theoretically have a higher data
bandwidth. If you're doing anything data intensive, like a sort in
memory, this could make a difference.

Would Opteron systems need 64-bit postgresql (and os, gcc, ...) build to have that advantage?

Well, that would give you the most benefit, but the memory bandwidth is
still greater than on a Xeon. There's really no issue with 64 bit if
you're using open source software; it all compiles for 64 bits and
you're good to go. http://stats.distributed.net runs on a dual opteron
box running FreeBSD and I've had no issues.

You can get 64-bit Xeons also but it takes hit in the I/O department due to the lack of a hardware I/O MMU which limits DMA transfers to addresses below 4GB. This has a two-fold impact:

1) transfering data to >4GB require first a transfer to <4GB and then a copy to the final destination.

2) You must allocate real memory 2X the address space of the devices to act as bounce buffers. This is especially problematic for workstations because if you put a 512MB Nvidia card in your computer for graphics work -- you've just lost 1GB of memory. (I dunno how much the typical SCSI/NIC/etc take up.)

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