Our ubuntu 20 vms run unbound version 1.9.4 received new ubuntu 22 vms and installed unbound version 1.13.1 via package manager. I have started noticing that on the ubuntu 22 machines, the *total.requestlist.exceeded* stat started getting non-zero values. unbound v1.9.4 in ubuntu 20, always shows 0.
The queries received by each node looks to be at most 20k or less and are distributed equally. All sysctl parameters are identical between ubuntu 20 and ubuntu 22 vms. Unbound config is identical on both. Most unbound.conf parameters are left to defaults, the following are the important ones I believe influence unbound performance. num-threads: 8 outgoing-range: 60000 num-queries-per-thread: 30000 so-reuseport: yes module-config: "iterator" msg-cache-slabs: 2 rrset-cache-slabs: 2 infra-cache-slabs: 2 key-cache-slabs: 2 rrset-cache-size: 512m msg-cache-size: 256m so-rcvbuf: 4m so-sndbuf: 4m Unbound service starts and occupies available ports and FDs. CPU and memory utilisation on both are very minimal. less than 25% # ulimit -n 1048576 unbound[764890:0] debug: total of 59463 outgoing ports available *Ubuntu 20 stats_noreset: * total.num.queries=15979 *total.requestlist.max=5**total.requestlist.exceeded=0* *total.requestlist.current.all=9total.requestlist.current.user=7* *Ubuntu22 **stats_noreset**: * total.num.queries=9157 *total.requestlist.max=5* *total.requestlist.exceeded=3total.requestlist.current.all=3total.requestlist.current.user=3* ubuntu 22 systems constantly have non-zero values. Ubuntu 20 systems and even Centos7 ( unbound version 1.7.1) always have zero. As per my understanding of the config parameters, the system itself has enough resources available to handle atleast 2x the current traffic. As a test I have compiled version 1.13.1 on a ubuntu 20 VM and still the request list exceeded stat is zero. On Ubuntu 22 I have also compiled and installed the latest unbound version 1.20.0 and it's still the same - non zero values. I can see that the queries dropped is less than 1 req/s but it's still confusing since its only seen on ubuntu 22 vms with little resource utilisation. Has anyone run into something similar ? Do you know if any ubuntu 22 specific parameters should be modified ? Happy to provide more information if needed.
