Re: [9fans] image/memimage speed

["ron minnich" <rminnich@gmail.com>]

On Mon, Dec 1, 2008 at 6:33 AM, erik quanstrom <quanstro@coraid.com> wrote:
>>
>> Very true, the only exception to this I know of is some of the modern
>> Dual PCIExpress cards which use a bus in each direction.
>>
>
> do you have a reference for "dual pciexpress"?  as far as i know,
> pcie/agp/pci cards only have a single bus that goes both ways.

how about this:
"SANTA CLARA, CA—JUNE 28, 2004—NVIDIA Corporation (Nasdaq: NVDA), the
worldwide leader in visual processing solutions, broadened its already
expansive graphics line today with the introduction of four new NVIDIA
Quadro(R) professional graphics solutions based on PCI Express™.
Leveraging this next-generation bus architecture, NVIDIA doubles the
bandwidth of its AGP 8X-based products to over 4GB per second in both
upstream and downstream data transfers.  "

I think the AGP assymetry is long gone. Back when I was at LANL the
graphics guys were telling me that read bandwidth was no longer an
issue with the new pcie cards.

If you're still seeing bad performance it may be because you need to
fix up the MTRR or GART settings. I've done this dance and have no
memory at this point of what you do, but vague memory is that proper
MTRR settings with a good PCIe card will give you far better bandwidth
than the old AGP cards. There is nothing like the 60x assymetry.

ron