CPU usage

RouterOS General
1

Hi,

We are an ISP and we are using about 21 450G router boards in different locations in some router boards the CPU usage is touching nearly 70-80%. Can anyone tell why is this happening and what i need to check.

I have nearly 200 hotspot users configured and 60-70 will be live.

Please tell me what would be the issue is there any issue with 450G router board or any configuration issue.

Thanks,
Srinivas

2

CPU usage relies upon a ton of variables, without knowing more about your setup, it is impossible to say what could be causing it.

How much bandwidth is going through the router during high CPU times?
How many packets per second is it receiving or dealing with?
What other services are you running on the router? (UserManager, TheDUDE, etc.)
How many Queues and firewall rules, mainly mangle rules?

Inefficient firewall rules will eat up a lot of CPU time, a lot of simple queues will also eat up a lot of time. The more services you have running on the router board, the more CPU time it takes as well, if I remember correctly UserManager takes up a lot of resources. A packet, no matter the size, takes up the exact same amount of resources to process, so bandwidth isn’t always a good indicator.

If you have the 5.0rcx installed, they have a TOP like feature that will tell you where your CPU is spending the most time.

3

Hi,

Bandwidth usage is around 9Mbps
There are no other services running, we run only one IP-tunnel, DHCP and hotspot.
Some 8-10 firewall rules are there and no mangle rules.

How to find out due to which the CPU usage is so high.

Thanks,
Srinivas

4

You need to update to the latest 5.0rc in order to get it. Keep in mind it is still in release candidate state so be careful uploading it to a production router if you want to do it.

Are you using the proxy at all? Do any of your firewall rules use the layer7 matcher? The hotspot itself can take up a fair amount of CPU time if not configured in a certain way for heavy usage. One thing that I’ve also noticed is that an end user using an FTP client will make the CPU spike rather heavily.

5

Srinivas

With the level of data given, it is difficult to know where to suggest, the above answers are a good start. Firewall rules, mangle rules, queues can be CPU intensive.

Do you have graphing enabled and does the CPU % match the traffic bandwidth exactly?

Looking at it another way, if the CPU is 60-70% why be worried? I would be a lot more worried if it were 100%!