zabbo

I’ve been working on an interesting project at work for a while now. It’s an implementation of a socket API that provides reliable message delivery over ethernet. I’m being brief here because we’re still going through the process of getting approval to share the code. The intent, of course, is to see it properly maintained in the kernel.

I’m excited because I’ve been testing it on some machines at work and have some encouraging results. The test is a little application that measure the time it takes to to get a response to a message that is sent to a machine who immediately just sends it right back. The machines are dual opterons with e1000 gigabit cards. The following table reports the fastest round trip time seen over a period of a few seconds.

(I apologize in advance for the awful style of this table, maybe I’ll try my hand at some CSS)

This is exciting for at least two reasons.

First, the latency is lower than TCP. This shows that users who want reliable messages but are sensitive to latency might well be interested in this. Some significant pieces of Oracle are certainly interested in low latency reliable messages, hence my involvement.

Secondly, it’s awfully close to the latency of UDP. There’s still enough room for improvement in the RDS/eth sending path to gain back that difference, I think. We could well get reliable messages with better latencies than UDP, which would make me smile.