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Operating Systems Linux Help pinpointing high HTTPD CPU usage in TOP Post 302265156 by pspace on Friday 5th of December 2008 05:39:33 PM
Old 12-05-2008
Thanks for helping! Per your post, I've researched the 'prefork MPM' section of my httpd.conf file but am not finding anything that helps me fine tune the settings for my particular server usage or server type.

I believe I saw some example .conf files that were like htppd-huge.conf htppd-large.conf htppd-small.conf and stuff like that. I went through each saw that the huge one was referring to a server with 4GB ram which is what mine has. I tried using those settings but my server didn't like it very much at all! Next I tried using the large and medium ones but again my server acted funny so I reverted back to what I have:
Code:
# 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
# ServerLimit: maximum value for MaxClients for the lifetime of the server
# MaxClients: maximum number of server processes allowed to start
# MaxRequestsPerChild: maximum number of requests a server process serves
<IfModule prefork.c>
StartServers       16
MinSpareServers    16 
MaxSpareServers   64
ServerLimit      512
MaxClients       512
MaxRequestsPerChild  4000
</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 worker.c>
StartServers         2
MaxClients         150
MinSpareThreads     25
MaxSpareThreads     75 
ThreadsPerChild     25
MaxRequestsPerChild  0
</IfModule>

There must be a way to limit the CPU usage of each httpd thread so that it doesn't reach 100% ? I read doc's on the Apache site that explained what each of the above does but it didn't help me figure out which way to go with things. Do I leave the worker.c alone above and focus on the prefork? You said to modify the FF but I don't know what FF stands for sorry. Smilie You pasted MaxClients, etc. so I'm assuming it's the prefork I should mess with.

Another thing that I tried was since the huge .conf file example had settings almost double mine, I attempted to double the settings such as changing StartServers to 32 from 16, all the way down the module list. That didn't work either.

We have more than 2GB of RAM that's not being used since Plesk usually says we're using between 1GB and 2GB, so I don't imagine this is memory related. Also since most threads in TOP show 0.3% cpu usage to 1.7%cpu usage, it seems to be a problem when I find 100% usage. For instance I got home an hour ago and killed 5 threads that were 100% cpu usage in TOP. I just checked now and see 2 more running and bogging down my server. There's a big difference between 0.6% and 100% I'd say Smilie Any further help for my confusion would be GREATLY appreciated!

Chris

Last edited by pspace; 12-05-2008 at 06:45 PM..
 

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dtc_install_centos(8)					      System Manager's Manual					     dtc_install_centos(8)

NAME
dtc_install_centos - bootstrap a CentOS install to use in a chroot or VM SYNOPSIS
dtc_install_centos <install root> <yum environment> DESCRIPTION
This shell script is part of the dtc-xen package, generally to be used by the dtc panel to install a new a Xen VPS server. This script is called by dtc_reinstall_os when the user chooses to install the CentOS operating system. How it works: it generates a temporary yum configuration in the yum environment directory, that directs yum to act inside the install root instead of in the base system; then it kindly requests yum to install the basesystem, centos-release and yum packages onto it. Yum then uses the configuration to download the required (usually, security-updated) packages and then perform the RPM installation process under the install root. It requires both RPM and yum. It does work under Debian (it was developed in Ubuntu first). It should also work on RPM-based systems without destroying the system-wide RPM and yum configurations. OPTION
<install root> Target directory where CentOS will be deployed. Must exist beforehand. <yum environment> Directory where yum will store the repository manifests and configuration. Will be automatically created. Cached RPMs and manifests will be left, as usual, in a directory var/cache/yum inside the install root. EXAMPLE
dtc_install_centos /root/yum /xen/13 This will setup the operating system in /xen/13, with the CentOS configuration folder in /root/yum. BUGS
It's limited to CentOS 5 at the moment. It must be run as root. Under some circumstances, the installation process itself may kill processes running on the host machine. The chroot yum does should be sufficient to avoid this, but we haven't been able, yet, to ascertain why this fails sometimes. SEE ALSO
dtc_reinstall_os(8) VERSION
This documentation describes dtc_install_os version 0.3.1. See http://www.gplhost.com/software-dtc-xen.html for updates. dtc_install_centos(8)
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