device to device bandwidth confusion?

davem_de · January 14, 2009, 5:01pm

Hello,

I did the following test:
bandwidthTest.exe --csv --memory=pinned --mode=range --dtod …

The result I got is a little bit confusing to me.

Thus, it is faster to copy a large amount of data than only a few thousands of bytes?
Can anybode explain this result to me?

Thank you very much!

David

davem_de · February 25, 2009, 9:06am

Nobody has a suggestion? Please… :)

Jamie_K · February 25, 2009, 9:35pm

I don’t get the same results

And in any case I would expect the resuts to be “strange” for very small transfers.

tmurray · February 25, 2009, 9:39pm

What’s your motherboard? It’s almost certainly a BIOS issue.

davem_de · February 26, 2009, 6:26am

Dell T5400 with IntelÂ® 5400 chipset and Nvidia Quadro FX 3700

I did the SDK Bandwidth test:

bandwidthTest.exe --csv --memory=pinned --mode=range --dtod --start=*** --end=*** --increment=***

A few minutes ago, I did the test again. Same results like first post, just more values in range.

bandwidthTest.exe --csv --memory=pinned --mode=range --dtod --start=8 --end=1024 --increment=8

bandwidthTest.exe --csv --memory=pinned --mode=range --dtod --start=1024 --end=32768 --increment=1024

bandwidthTest.exe --csv --memory=pinned --mode=range --dtod --start=32768 --end=524288 --increment=32768

bandwidthTest.exe --csv --memory=pinned --mode=range --dtod --start=524288 --end=16777216 --increment=524288

bandwidthTest.exe --csv --memory=pinned --mode=range --dtod --start=16777216 --end=134217728 --increment=16777216

Here the bandwidth:

Here the time, calculated as follows:

Time [s] = Transferred_Data [Byte] / (Bandwidth [MB/s] * 1024 * 1024)

What do you mean with BIOS issue. In Detail?