KVM Virtual Machine high load average but low cpu and ram usage-why?

Question

I have a web server with nginx and php-fpm 5.6. It is one virtual machine of KVM. Here is ovs between VMs. The parameters of this Vm are : 4 CPU, 6GB RAM and 50 GB disk with raw, Debian 8.6. There are every 15 minutes load average increases and number of php-fpm processes also increases. I have tested and deleted all jobs from cron. When load average increases input and output traffic accordingly. How can I solve this problem ? I already spent 3 days on it. Here is my screenshots:

Answer 1

You appear to have a saturation problem where the number of tasks to run jumps up for a minute or two. It apparently happens on an interval.

Try to get a system resources summary during the minute when it happens, such as with vmstat 5. Presumably the runnable processes column r will be large when there is no idle CPU ('id' column).

Looking at the access log for the HTTP requests might give an idea of who the clients are and what they are doing. One way is to use a top-style monitor like ngxtop.

To mitigate the problem, assuming it is php-fpm, you can control the number of processes. Check your configured value for pm.max_children. You will need to experiment a little to find the correct tuning. Probably something like 8 will not be too excessive.