WordPress MU

I am running WPMU with about 700+ blogs for a school district. I have noticed a huge spike in CPU utilization. We use only 4 plugins: WP-Gallery Remote, Google Translator, Podpress, and Events Calendar which may or may not be activated on each blog.

We are getting spikes from 2500 Mhz to 3500 Mhz. We are using Ubuntu Server and running it on a VMware server. The average during the school day is about 2600 Mhz and drops to near 200Mhz after 12pm until school starts the next day.

Because it is VM, we can give it more power but we are wondering if something else is going on that is causing the spikes during the day. We have other servers that hardly use so much power. One other thing of note: Each school website runs on Deki Wiki and utilizes Deki's built in RSS reader for displaying recent posts from teacher blogs on the school websites. So each time someone loads the Staff Pages from the school website, it hits the WPMU server and loads the Recent RSS feed items from the teachers blog. There can be anywhere from 12-20 RSS feeds it is processing when the staff page loads from the WPMU server.

Is this normal? Does WPMU require this much power for the larger sites? IF not, what can I do to cut down on the server CPU use?

You may look at redesigning the interface to the Staff Pages. Could be that you are loading WPMU with ALL blogs in full each time that page is accessed, depending on how you are grabbing the RSS feeds.

An idea would be to keep a go-between that handles the feeds and is easily polled when the Staff Page loads and only handles the recent blog posts. Have that update hourly or half hourly and that way if you get 10 visitors in 10 minutes they are generating minimal traffic instead of each one reloading the WPMU site.

I hope that makes sense, and it should drop your server load by a noticeable amount.

I will look into it.

What is using the CPU? Is it the webserver or the mysql processes? or is it the o/s itself (a top command will give you information on what sort of process is using the CPU)

It appears to be MySql at the highest % followed by Apache. My SQL is generally 7-15% of CPU while the various instances of Apache run each at about 5-8% each.

Can I tweak MySql to make it more efficient? Give it more memory or what and How???

You can try optimizing the sql tables which will help if they've not been optimized for a while and you can tune mysql quite a bit to improve performance. There have been several threads on the subject in the past

Just this morning the server was operating at 3600Mhz Cpu utilization. I installed the WP-Super-Cache plugin and instantly dropped the CPU to around 250Mhz average.

HATS OFF TO THE CREATOR OF THIS PLUGIN. It installed and worked perfectly. Just the minor updates to the .htaccess files and I was on my way to saving my server.

Just out of curiosity, how many DB querries occur to load an average page? I think that was the main culprit. We had no other cache system running such as eAccellerator etc, so it was all on MySql and Apache to bring up the pages to over 700 blogs.

The creator of the plugin is the MAIN DEV of WPMU in general :) All salute Donncha!

Trent

How was the problem resolved? We're experiencing the same.

If you read a couple replies up, the OP installed the WP-Super-Cache plugin.