Подскажите по prefork и worker

Сабж, ось Дебиан, в httpd.conf имеется следущее:

# prefork MPM

# StartServers: number of server processes to start

# MinSpareServers: minimum number of server processes which are kept spare

# MaxSpareServers: maximum number of server processes which are kept spare

# MaxClients: maximum number of server processes allowed to start

# MaxRequestsPerChild: maximum number of requests a server process serves

<IfModule mpm_prefork_module>

    StartServers          5

    MinSpareServers       5

    MaxSpareServers      10

    MaxClients          150

    MaxRequestsPerChild   0

</IfModule>



# worker MPM

# StartServers: initial number of server processes to start

# MaxClients: maximum number of simultaneous client connections

# MinSpareThreads: minimum number of worker threads which are kept spare

# MaxSpareThreads: maximum number of worker threads which are kept spare

# ThreadsPerChild: constant number of worker threads in each server process

# MaxRequestsPerChild: maximum number of requests a server process serves

<IfModule mpm_worker_module>

    StartServers          2

    MaxClients          150

    MinSpareThreads      25

    MaxSpareThreads      75 

    ThreadsPerChild      25

    MaxRequestsPerChild   0

</IfModule>

Должен быть подключен только один модуль или я ошибаюсь?