CRS518: high CPU for each additional port running (since ROS 7.9)

RouterOS General
1

We found that in CRS518-16XS-2XQ, for every port with a module inserted, even with NO traffic flowing, there is an addition 5-7% of CPU usage!

It’s not a problem with a specific board: we verified this behaviour with three different CRS518 boards.

It’s NOT a problem of configuration: we loaded ROS 7.10 and RESET the configuration, so that NO CONFIGURATION is present. With no port connected we have 0% CPU usage. With each port connected we have 5-7% more CPU usage. With 3 ports connected (NO traffic flowing!) we have 15-20% of CPU usage!

As you can see, no IRQ usage, only CPU.
CRS518_CPU.png
We tried with DAC (Mikrotik) and Fiber modules (XSFP and SFP+).

We found that this happens with ROS 7.9, 7.10 and 7.11-beta2.

The problem IS NOT PRESENT with ROS 7.8 (and maybe previous versions, but not tested currently).

Is this a known problem?
Is there any solution? (apart from downgrade to 7.8)

Thanks.

2

Can confirm that we’re also having the same issue with our crs518 switches. In our case we’re using librenms to pull snmp statistics from the switch. Using ros 7.10 it takes almost 2 minutes for one snmp pull to complete. Downgrading to 7.8 and the pull time went down to 15 seconds.

3

I have seen this in the just released 7.11beta5:

  • sfp - reduce CPU load due to SFP interface handling for CCR2116, CCR2216, CCR2004-12S+2XS, CRS312, CRS518 devices (introduced in v7.9)