By realtime I mean something that can help with fast network I/O; Low-latency and high-throughput.
1 Answers
I'd say CentOS or Scientific Linux with a realtime kernel compiled from Red Hat MRG source RPMs or using the CERN pre-built binaries.
See: Compiling realtime kernel from RHEL 6 MRG sources on CentOS 6
The caveat is that simply installing a realtime distro won't automagically make everything faster. These kernels and related tools give you more "knobs" to tweak and ways to measure performance. This can be done for free (I've done it), but you will have to invest the time into working with your application and environment. Using the option I outlined, you can at least start with the RHEL MRG Tuning Guide.
On the tuning side, there's a lot more to work with in this realm. E.g.
- Familiarize yourself with Ethtool and its options.
- Investigate how interrupts work. E.g. what really happens when a NIC generates an interrupt. What does setting /proc/irq/irq_number/smp_affinity really do?
- Understand CPU/process binding and realtime/rtctl priorities.
Other options include the commercial Concurrent RedHawk Linux (RHEL-like) and SuSE Enterprise Realtime. But they are costly distributions.