email@example.com (Bruce Momjian) wrote: > William Yu wrote: >> > 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.) > > I thought Intel was copying AMD's 64-bit API. Is Intel's > implementation as poor as you description? Does Intel have any better > 64-bit offering other than the Itanium/Itanic?
>From what I can see, the resulting "copy of AMD64" amounts to little more than rushing together a project to glue a bag on the side of a Xeon chip with some 64 bit parts in it. I see no reason to expect what is only billed as an "extension technology" <http://www.eweek.com/article2/0,1759,1545734,00.asp> to alleviate the deeply rooted memory bandwidth problems seen on Xeon. -- let name="cbbrowne" and tld="acm.org" in name ^ "@" ^ tld;; http://cbbrowne.com/info/advocacy.html Q: What does the function NULL do? A: The function NULL tests whether or not its argument is NIL or not. If its argument is NIL the value of NULL is NIL. -- Ken Tracton, Programmer's Guide to Lisp, page 73. ---------------------------(end of broadcast)--------------------------- TIP 7: don't forget to increase your free space map settings