Preliminary testing shows the 2.6.0-test9 kernel handily beating 2.4.22 on x86 and ia64. The x86_64 support is still somewhat iffy, so I can't fully test that platform, which is bothering me; I still can't boot a stable 2.4.x SMP kernel or any 2.6.0 branch kernel on dual 248s with the MSI Master2-FAR Opteron SMP board. This includes the SMP x86_64 2.4.21EL kernel shipped by RedHat in AS 3.0 or the 2.4.19 kernel shipped with SuSE SLES. a 2.4.23rc3 kernel builds and boots, addressing both CPUs, but the RTC is inaccessible, so it needs a patch that I can't locate at the moment.
That said, on the one 2.2Ghz Opteron 248 CPU I can address with the RH kernel, I can `make dep && make bzImage` 2.4.22 vanilla in 2m41s. A dual 2.4Ghz P4 XEON HT box clocks in at 3m42s for the same compile. Interesting. Needs verification. It would be nice to look at the MySQL benchmarks on the Opteron box, but the AMD64 MySQL server binary runs away and spins when it's invoked. Compiled from source, from an RH SRPM, from a MySQL RPM, v3.28 or v4.0.16 -- no love. No wonder RedHat forgot to include mysql-server in the RH AS 3.0 distro.