Yes, I experienced similar issue in my application. In a short answer, set the swqs write burst value to 1 may reduce the latency significantly. The default write burst value is 32.
On Mon., Feb. 17, 2020, 8:41 a.m. Victor Huertas <vhuer...@gmail.com> wrote: > Hi all, > > I am developing my own DPDK application basing it in the dpdk-stable > ip_pipeline example. > At this moment I am using the 17.11 LTS version of DPDK and I amb observing > some extrange behaviour. Maybe it is an old issue that can be solved > quickly so I would appreciate it if some expert can shade a light on this. > > The ip_pipeline example allows you to develop Pipelines that perform > specific packet processing functions (ROUTING, FLOW_CLASSIFYING, etc...). > The thing is that I am extending some of this pipelines with my own. > However I want to take advantage of the built-in ip_pipeline capability of > arbitrarily assigning the logical core where the pipeline (f_run() > function) must be executed so that i can adapt the packet processing power > to the amount of the number of cores available. > Taking this into account I have observed something strange. I show you this > simple example below. > > Case 1: > [PIPELINE 0 MASTER core =0] > [PIPELINE 1 core=1] --- SWQ1--->[PIPELINE 2 core=2] -----SWQ2----> > [PIPELINE 3 core=3] > > Case 2: > [PIPELINE 0 MASTER core =0] > [PIPELINE 1 core=1] --- SWQ1--->[PIPELINE 2 core=1] -----SWQ2----> > [PIPELINE 3 core=1] > > I send a ping between two hosts connected at both sides of the pipeline > model which allows these pings to cross all the pipelines (from 1 to 3). > What I observe in Case 1 (each pipeline has its own thread in different > core) is that the reported RTT is less than 1 ms, whereas in Case 2 (all > pipelines except MASTER are run in the same thread) is 20 ms. Furthermore, > in Case 2, if I increase a lot (hundreds of Mbps) the packet rate this RTT > decreases to 3 or 4 ms. > > Has somebody observed this behaviour in the past? Can it be solved somehow? > > Thanks a lot for your attention > -- > Victor > > > -- > Victor >
