Configuring HAProxy+nginx+PHP-FPM to out perform Apache+mod_php - apache

Question

Edit
Running my OS on the VirtualBox was the issue. As soon as I made my OS the native on the disk, I was able to see the performance boost.
Original
I've read a lot of people recommend ditching Apache+mod_php for HAProxy+nginx+PHP-FPM. I'm trying to verify that it's a more efficient setup, but am not seeing the results people describe. Both siege and ab (Apache Benchmark) are showing that Apache at any number of concurrent connections is giving better responses per second, and can support more connections .
I'm running Ubuntu 11.04 server on VirtualBox. It has 10 gigs of space, and 1,344 megs of memory. I used apt-get for installing the programs mentioned above. Here are the related config files with just the important parts included.
haproxy.cfg
global
maxconn 4096
user haproxy
group haproxy
daemon
stats socket /var/run/haproxy.sock mode 0600 level admin
defaults
log global
mode http
option httplog
option dontlognull
retries 3
option redispatch
maxconn 2000
contimeout 5000
clitimeout 50000
srvtimeout 50000
listen tcpcluster *:80
mode tcp
option tcplog
balance roundrobin
server tcp01 192.168.1.199:8080 check
nginx.conf
worker_processes 2;
events {
worker_connections 768;
}
www.conf
pm = dynamic
pm.max_children = 10
pm.min_spare_servers = 2
pm.max_spare_servers = 4
pm.max_requests = 500
apache.conf
<IfModule mpm_prefork_module>
StartServers 5
MinSpareServers 5
MaxSpareServers 10
MaxClients 10
MaxRequestsPerChild 0
</IfModule>
<IfModule mpm_worker_module>
StartServers 2
MinSpareThreads 25
MaxSpareThreads 75
ThreadLimit 64
ThreadsPerChild 25
MaxClients 10
MaxRequestsPerChild 0
</IfModule>
<IfModule mpm_event_module>
StartServers 2
MinSpareThreads 25
MaxSpareThreads 75
ThreadLimit 64
ThreadsPerChild 25
MaxClients 10
MaxRequestsPerChild 0
</IfModule>
Given that PHP-FPM and Apache both have a maximum of 10 children, I would expect that any speed advantage would be visible. In every test I've run (always waiting until load is 0.01 before I run the test), Apache is always able to handle more request more efficiently.
Is there some other optimization that can be made so that the setup best suited to scale will outperform the setup that should not be more efficient?

Answer 1

Use haproxy as a connection concentrator : use "mode http" instead of "mode tcp", use "option http-server-close" and set a server maxconn value well below the worker connections value. You should cross a point where the lower concurrency brings much more performance with much lower RAM usage and better cache efficiency along the whole chain.
BTW, what are the numbers we're talking about ? Do they measure in hundreds or in thousands of requests per second ? Because clearly, the application server will make a real difference only in the higher loads. Obviously if the application runs very slowly, there is no reason to see a difference when replacing the server.