Weird system load peaks

koloth · 11-05-2015, 04:28 AM

Hi there,

I have a server running Drupal on Centos 6.6.

In general handles well however i have those occasional spikes in CPU usage, specifically around 90%sy.

It is my understanding that none of the apps running (apache,mysql,varnish) would show up as system usage and there is no increase in traffic.

Any ideas on what i should check?

thanks

berndbausch · 11-05-2015, 06:22 AM

Do you see those 90% peaks live? Then just run top to find the culprit.
Do you see them after the fact, e.g. as a sar report? Perhaps process accounting will help https://www.gnu.org/software/acct/ma...ccounting.html, or are there more modern utilities?

Quote:

It is my understanding that none of the apps running (apache,mysql,varnish) would show up as system usage

If by "system usage" you mean system CPU, you are wrong. System CPU usage is accumulated when kernel code is executed. A process that issues many system calls, for example a lot of IO, would have a high system CPU usage.

By the way, consider updating to 6.7 (yum upgrade).

koloth · 11-06-2015, 03:50 AM

Quote:

Originally Posted by berndbausch

If by "system usage" you mean system CPU, you are wrong. System CPU usage is accumulated when kernel code is executed. A process that issues many system calls, for example a lot of IO, would have a high system CPU usage.

thanx for the reply,

I do mean system CPU and i've noticed that varnishd exceeds its memory limit so that could be the case...

By the way the induced downtime kind of limits my upgrade to 6.7 options