I have updated the kernel on an Ubuntu server from 3.13.0-32-generic to 3.19.0-031900-lowlatency. I have a single C++ application running on this server that processes large amounts of data it receives over multicast, does some processing and multicast the results. The low latency kernel have definitely improved performance. The processing numbers have been reduced by 30% for processing of each packet.
But the publishing time have gone worse at higher percentiles,. To calculate the publishing time I take counters before and after a SendTo() call. Below are the performance numbers of SendTo call in microseconds.
Percentile GenericKernel LowLatencyKernel
10 2.9 2.6
50 2.9 2.7
95 3.6 4.8
99 4.6 6.2
Any insights on why the SendTo call have gone slow. And what can be done to improve this to be atleast same as when using generic kernel.