2016-04-14 - docker networking performance

today Sławek pointer my attention to the fact, that networking is much slower inside docker containers, than it is on host… and indeed it is – almost by half!

the test scenario was simple. on host machine i've launched simple application, that generated ~2GB/s of pseudo-random garbage, that was piped though ncat to the other side. other side was:

loopback interface (as a reference point)
docker container started with own networking (default)
docker container started with host's networking (–net=host option)

here are the results (average of 4 runs, 10GB transfer each):

test	speed [MB/s]	performance loss [%]
loopback	707	0
docker with own networking	385	45
docker with host networking	688	3

it is clear now that host network should be used for network-sensitive applications. default (better separation at the cost of performance) is probably good for everything else. ;)