Most of modern applications operate on milliseconds timescale. However, sometimes you need 1000 times better resolution - microseconds instead of milliseconds. Most probably, in this case you also need jitter to be as low as possible. There are areas where 'fast on average' is not acceptable and 'guaranteed fast for every request' is required.
In modern financial services robots fight robots and several microseconds sometimes determine the winner - jitter can cost millions of dollars. In command and control systems cost of jitter just can not be expressed in dollars at all. In telecommunications you need a predictable packet flow to provide stable audio or video connection. Even in many online games you need this kind of determinism to provide fair conditions for participants.
General purpose operating systems were not designed for these workloads. If your application requires microseconds determinism - you need real time operating system. Optimizing your applications for real time is challenging, but it gives you serious competitive advantage. We have built real time solutions based on Red Hat Enterprise Linux for Real Time for several very demanding customers. Now we are ready to assist you in your real time project. Details are available on request, please, contact us for additional information.