How to temporarily buffer incoming network traffic for latency-sensitive HFT application?

Question

We are running a Java-based trading application, and there are certain periods where we want to prioritize outgoing network traffic as much as possible for about 10 ms. Is there a way to temporarily buffer all incoming network traffic during a short time period, either on the network card or via a process or buffer on our Redhat Linux box?

The rationale behind this is that the incoming network traffic spikes during this same period, and the application processing this traffic is stealing CPU cycles from the process we are trying to prioritize. We do not have fine-grained control over the application treating the incoming network traffic.

We're on a 1 Gbps connection so a buffer of about 1 MB should be sufficient. We would prefer not dropping the incoming traffic and requesting retransmission as this would increase load on our network during quite busy periods.

Answer 1

Possible using Qos on the router, or using trickle to control your bandwidth by a sample configuration of :

   /etc/trickled.conf.

see example in url.

Answer 2

I am not sure whether I understand your problem correctly. Your concern is sometimes you have priority to deal with output network traffic and at this time the incoming traffic will build up and finally might cause package drop or retransmission which you don't want. Therefore, you want to buffer your incoming traffic.

If my understanding is correct and your are using TCP, try to make your tcp buffer bigger. http://kaivanov.blogspot.com/2010/09/linux-tcp-tuning.html and then Use netstat to check whether your change is effective.

Answer 3

Adrian, have you tried setting the priority of your outgoing communication process to be higher than that of the process receiving the incoming data? Using the nice command this can be achieved. Note that in Unix/Linux the lower the number the higher the priority.

Otherwise I am not sure this is possible without having a direct tie in between the two applications that are sending / receiving, allowing you to effectively ignore the incoming connections that are ready to read from until any data you have is sent out.