High CPU usage after upgrading from Debian 7 to Debian 9
I have two Debian boxes acting as a routesr (+iptables +quagga(BGP)). I have updated one from Debian 7 to Debian 9 recently and now experience 2x CPU utilization on the same amounts of traffic, e.g. on normal load of 1Gbps (real-world traffic) Debian 7 had 5-6% and Debian 9 has 10-12% softirq CPU time. This behaviour can also be observed during tests - 6Gbps iperf gets 3% on Debian 7 and 6% on Debian 9.
I compared ethtool -k outputs on both boxes and they are pretty similar. Syslog doesn't show anything suspicious.
Did anyone have the similar issue? Or can give me some advice on troubleshooting?
Any help will be appreciated.