From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kai Zhang Subject: About round trip latency with DPDK Date: Wed, 23 Jul 2014 15:24:49 -0400 Message-ID: Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 To: "dev-VfR2kkLFssw@public.gmane.org" Return-path: List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces-VfR2kkLFssw@public.gmane.org Sender: "dev" 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