Linux 2.6 kernel optimisations for HLDS

[grievah]

Hello,

Having just recompiled a 2.6.15.3 kernel, I wondered if any of you had managed to figure which kernel options are best to handle HLDS.

The machine:
- single Xeon 3.0Ghz HT
- 1.5 GB DDR

The goals:
- host two 16x tick rate 100 servers
- reduce CPU usage


With the kernel I compiled, 10 users on a tick rate 100 generate 25% CPU usage. By extrapolation, I get to 80-90% usage when both 16x servers are full.


Here's what I thought of, so far:
- SMP (to take advantage of HT and have one server run on each logical CPU)
- Time Frequency: enable 1000 Hz.

But what about:
- IO scheduler: Anticipatory, Deadline or CFQ?
- Preemption model: no preemption, volontary kernel preemption or preemptible kernel?
- kernel irq balancing?

Any of you already did benchmarks on those settings?

Would a timer frequency of 250 Mhz be enough to run tick rate 100 servers?
The advantage would be:
- less interrupts overhead
The inconvenient:
- probably 125 fps calculation, but that is enough to generate 100 ticks? Thoughts on this?

Any other settings of interest you know of, in the kernel, to save CPU cycles in an HLDS environment?