6.0 Stable on 8 Core AMD Opteron scalability.

[astatech at mail.ru]

Hi all!
Please help solve problem. I have following server:
- 8 cores at 2.2GHz/16GB RAM
- FreeBSD 6.0 kernel compiled with SMP support for amd64 (4BSD scheduler, maxusers=2048, disabled unused hardware)
- Apache, PHP, Mysql
- 1GBit NIC (bge)
I perform some benchmark and have very strange results with scalability. I start getting timeouts on client side after at 256 client threads, but CPU idle on server 30-40%. The top utility display that almost all httpd processes running on 7s core, and other 3-4 cores are idle.
I am sure that bottleneck not on client side or server physical IO/memory. 
With 256 threads I get 30 Requests\sec on FreeBSD and 280 Requests\sec on Solaris (100% load).

What can I do to utilize all CPU power on FreeBSD?

WBR, Alex.