How to optimize performance for a docker container?

Question

I tested redis container based on. https://index.docker.io/u/dockerfile/redis/

With same redis-benchmark, redis-server runs inside a container much slower, than run on hosted OS, the actual statistics shown below. ( The first benchmark is for a docker container )

So, is there a way to optimize the performance for a docker container?

vagrant@precise64:/tmp$ redis-benchmark -p 49153 -q -n 100000
PING (inline): 5607.27 requests per second
PING: 6721.79 requests per second
MSET (10 keys): 6085.69 requests per second
SET: 6288.91 requests per second
GET: 6627.78 requests per second
INCR: 6454.11 requests per second
LPUSH: 6449.12 requests per second
LPOP: 5355.90 requests per second
SADD: 6237.91 requests per second
SPOP: 6794.40 requests per second
LPUSH (again, in order to bench LRANGE): 6089.76 requests per second
LRANGE (first 100 elements): 6000.24 requests per second
LRANGE (first 300 elements): 4660.70 requests per second
LRANGE (first 450 elements): 4276.79 requests per second
LRANGE (first 600 elements): 3710.85 requests per second

vagrant@precise64:/tmp$
vagrant@precise64:/tmp$ sudo /etc/init.d/redis-server start
Starting redis-server: redis-server.
vagrant@precise64:/tmp$ redis-benchmark -q -n 100000
PING (inline): 19357.34 requests per second
PING: 19175.46 requests per second
MSET (10 keys): 16697.28 requests per second
SET: 19146.08 requests per second
GET: 19175.46 requests per second
INCR: 19135.09 requests per second
LPUSH: 19168.10 requests per second
LPOP: 14976.79 requests per second
SADD: 16638.93 requests per second
SPOP: 18079.91 requests per second
LPUSH (again, in order to bench LRANGE): 18268.18 requests per second
LRANGE (first 100 elements): 16136.84 requests per second
LRANGE (first 300 elements): 11528.71 requests per second
LRANGE (first 450 elements): 9237.88 requests per second
LRANGE (first 600 elements): 8864.46 requests per second

Answer 1

The container appears to be slower because you are going through an extra network layer.

In that case, instead of connecting directly to Redis, to connect to the Docker userland proxy, which itself connects back to the container (and instead of going over a local interface, this connection goes over a veth interface).

This adds a little bit of latency (not measurable compared to, e.g, a 10ms webpage generation; but 50µs is still faster than 150µs, if you see what I mean).

If you want to do a more "apples to apples" comparison, you could:

• run redis-benchmark inside the container (to connect directly to Redis from within the container);
• run redis-benchmark on another machine (but keep in mind that you will still have an extra network layer for the port translation mechanism);
• run redis-benchmark on another machine and use a mechanism like pipework to give the container a macvlan interface with (almost) zero overhead.