[knot-dns-users] Knot-DNS unused cores

I perfoms benchmarks with knot-dns as a authoritative server and dnsperf as a workload client. Knot server has 32 cores. Interrupts from 10Gb network card are spreaded across all 32 cores. Knot configured with 64 udp-workers. Each knot thread assigned to one core. So there are at least two knot threads assigned to one core. Then i start dnsperf with command ./dnsperf -s 10.0.0.4 -d out -n 20 -c 103 -T 64 -t 500 -S 1 -q 1000 -D htop on knot server shows 3-4 cores completly unused. Then i restart dnsperf unused cores are changes. That is the reason for unused core?