PCIX DMA Serverworks chipset

[Matthias Müller]

Hi,
I'm using the Xilinx PCI-X core (64bit/133MHz) on an add in card to
perform a DMA from the card into the system's memory. The user
application in the FPGA requests 4Kbyte bursts and after transfering the
4Kbyte it gets a new address from the device driver.
This application works well in a PC with Intel E7505 memory controller
and P64H2 bridge. We achieve a datarate of about 450 MB/s. But it
doesn't work in a HP Proliant DL380 with Serverworks Grand Champion LE
chipset and CIOB-X2 bridge. In this system we only can transfer data for
some seconds if the blocksize of the DMA is reduced to 1 Kbyte and then
the system suspends and has to be rebooted.
Does anyone have experience with a dma application on such a system?
Thank you,
Matthias

 

[Mark Schellhorn]

We are debugging similar types of issues with a Xilinx based PCI-X card and the
chipsets you mention. There are numerous possible causes for the general symptom
you describe. I presume these are dual Xeon chassis' you are talking about? Make
sure your s/w guys understand read/write ordering and use of semaphores in
multi-threaded applications and SMP systems.

My first suggestion is to get the documentation for the PCI-X bridge that you
are interfacing with. For the particular chipset that you describe that could
prove difficult .

My second suggestion is to buy one of these (or something like it):

http://www.futureplus.com/products/fs2007/pcix_summary.html

and hook it up to your logic analyzer (you can rent one too, that's what we
did). Being able to observe what's going on on that bus will save you a _lot_ of
debugging time.

Mark


Matthias Müller wrote:

Hi,
I'm using the Xilinx PCI-X core (64bit/133MHz) on an add in card to
perform a DMA from the card into the system's memory. The user
application in the FPGA requests 4Kbyte bursts and after transfering the
4Kbyte it gets a new address from the device driver.
This application works well in a PC with Intel E7505 memory controller
and P64H2 bridge. We achieve a datarate of about 450 MB/s. But it
doesn't work in a HP Proliant DL380 with Serverworks Grand Champion LE
chipset and CIOB-X2 bridge. In this system we only can transfer data for
some seconds if the blocksize of the DMA is reduced to 1 Kbyte and then
the system suspends and has to be rebooted.
Does anyone have experience with a dma application on such a system?
Thank you,
Matthias