Linux 2.4 has been around in production environments at companies for a few years now, we have been able to gather some good data on how well (or not) things scale up. Number of CPU's, amount of memory, number of processes, IO throughput, etc.
Most of the deployments in production today, are on relatively small systems, 4- to 8-ways, 8 - 16GB of memory, in a few cases 32GB. The architecture of choice has also been IA32. 64-bit systems are picking up in popularity rapidly, however.
Now with 2.6, a lot of the barriers are supposed to be gone. So, have they really? How much memory can be used now, how is cpu scaling these days, how good is IO throughput with multiple controllers in 2.6.
A lot of people have the assumption that 2.6 resolves all of this. We will go into detail on what we have found out, what we have tested and some of the conclusions on how good the move to 2.6 will really be.