Kai, the latency depends both on what you do and how much you send. A bigger packet will take longer time to transmit.
Now that thats out of the way I propose you use perf to see how busy is the cpu and with what. FYI, ~10us is something that can be achieved with netperf with a kernel driver based on interrupts. The 0.7m latency indicates that something is wrong with your system. Basically make sure that the cpu is busy with polling only and a small percent handling the messages. Hope this helps somehow. On Wed, Jul 23, 2014 at 10:24 PM, Kai Zhang <zhang.4522 at osu.edu> wrote: > Hello, > > I am trying to develop a low-latency application, and I measured the round > trip latency with DPDK. However I got an average of 650~720 microseconds > round-trip latency with Intel 82599 10Gbps NIC. > > The experiment method is as follows. 2 machines (A and B) are connected > back-to-back. Machine A embeds a time stamp in the packet and sends to B, B > (use testpmd or l2fwd) forwards packets back to A immediately (A->B->A), > and A receives packets and calculates time difference between current time > and the embedded time stamp. (code : > https://github.com/kay21s/dpdk/tree/master/examples/recv_send) > > I have 3 machines, and performing the above experiment on each pair leads > to a similar latency. However, previous academic papers report that DPDK > offers only a few 10 microseconds round trip latency. > > What's the round trip latency DPDK is supposed to offer? Have you measured > it at Intel? > > Thanks a lot, > Kai
