======= 2016-04-14 - docker networking performance =======

{{ :blog:2016:04:14:docker_logo.png?600|docker logo}}
today [[http://szborows.blogspot.co.at|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. ;)