Measuring DMA Activity

Discussion created by elesueur on Jun 22, 2009
Latest reply on Jun 25, 2009 by stroia


I have several Opteron test machines. I would like to profile some code, and at the same time measure the amount of DMA activity happening in the system.

The DMA would be caused by both network and disk IO.

I see in the Bios & Kernel Developers guide that there is a PMU event (ECh - probe responses and upstream requests). I can measure the number of requests generated by upstream devices (like network or disk controller separately from display refresh requests) but that doesn't tell me the size of each request.

Has anyone tried to measure the rate of DMA activity in an opteron system before?