Hi,

We run around 50 knot servers around the world, with great success - thanks for the software!

We are just a little curious about seemingly high CPU usage, and how best to interpret the results, if someone could advise?  Specifically, we are seeing the majority of the cpu time in 'system' and not 'user', what would that suggest is happening perhaps?

Any tuning help gratefully received! 

Our platform (sample)

24 Core CPU E5-2440 0 @ 2.40
64Gb RAM
SSD

knot-2.9.5, running on Centos 8.2

Currently receiving around 4k pps

Server is authoritative for a 278 zones, the largest zone file being around 600Mb

Output of top

top - 20:50:38 up 6 days,  4:49,  2 users,  load average: 13.47, 12.34, 11.83
Tasks: 321 total,   2 running, 318 sleeping,   0 stopped,   1 zombie
%Cpu0  :  4.0 us, 34.1 sy,  0.0 ni, 60.3 id,  0.3 wa,  0.7 hi,  0.7 si,  0.0 st
%Cpu1  :  4.3 us, 19.4 sy,  0.0 ni, 75.3 id,  0.0 wa,  0.3 hi,  0.7 si,  0.0 st
%Cpu2  :  4.3 us, 33.8 sy,  0.0 ni, 60.9 id,  0.0 wa,  0.7 hi,  0.3 si,  0.0 st
%Cpu3  :  5.0 us, 21.2 sy,  0.0 ni, 73.2 id,  0.0 wa,  0.3 hi,  0.3 si,  0.0 st
%Cpu4  :  3.3 us, 34.9 sy,  0.0 ni, 61.5 id,  0.0 wa,  0.3 hi,  0.0 si,  0.0 st
%Cpu5  :  3.0 us, 20.2 sy,  0.0 ni, 76.2 id,  0.0 wa,  0.3 hi,  0.3 si,  0.0 st
%Cpu6  :  4.0 us, 35.2 sy,  0.0 ni, 60.4 id,  0.0 wa,  0.3 hi,  0.0 si,  0.0 st
%Cpu7  :  5.0 us, 18.7 sy,  0.0 ni, 76.0 id,  0.0 wa,  0.3 hi,  0.0 si,  0.0 st
%Cpu8  :  2.0 us, 35.0 sy,  0.0 ni, 62.3 id,  0.0 wa,  0.7 hi,  0.0 si,  0.0 st
%Cpu9  :  2.0 us, 20.0 sy,  0.0 ni, 77.7 id,  0.0 wa,  0.3 hi,  0.0 si,  0.0 st
%Cpu10 :  3.7 us, 34.4 sy,  0.0 ni, 61.2 id,  0.0 wa,  0.7 hi,  0.0 si,  0.0 st
%Cpu11 :  3.3 us, 20.7 sy,  0.0 ni, 75.7 id,  0.0 wa,  0.3 hi,  0.0 si,  0.0 st
%Cpu12 :  2.3 us, 34.6 sy,  0.0 ni, 62.1 id,  0.0 wa,  0.7 hi,  0.3 si,  0.0 st
%Cpu13 :  3.3 us, 20.7 sy,  0.0 ni, 75.7 id,  0.0 wa,  0.3 hi,  0.0 si,  0.0 st
%Cpu14 :  2.3 us, 33.6 sy,  0.0 ni, 59.7 id,  0.0 wa,  0.7 hi,  3.7 si,  0.0 st
%Cpu15 :  3.3 us, 19.7 sy,  0.0 ni, 76.3 id,  0.0 wa,  0.3 hi,  0.3 si,  0.0 st
%Cpu16 :  2.3 us, 34.0 sy,  0.0 ni, 58.7 id,  0.0 wa,  1.0 hi,  4.0 si,  0.0 st
%Cpu17 :  2.3 us, 21.5 sy,  0.0 ni, 75.8 id,  0.0 wa,  0.3 hi,  0.0 si,  0.0 st
%Cpu18 :  3.3 us, 34.8 sy,  0.0 ni, 57.2 id,  0.0 wa,  0.7 hi,  4.0 si,  0.0 st
%Cpu19 :  5.0 us, 19.3 sy,  0.0 ni, 75.1 id,  0.0 wa,  0.3 hi,  0.3 si,  0.0 st
%Cpu20 :  2.7 us, 35.3 sy,  0.0 ni, 60.0 id,  0.0 wa,  0.7 hi,  1.3 si,  0.0 st
%Cpu21 :  1.7 us, 20.5 sy,  0.0 ni, 77.2 id,  0.0 wa,  0.3 hi,  0.3 si,  0.0 st
%Cpu22 :  4.7 us, 32.4 sy,  0.0 ni, 58.5 id,  0.0 wa,  0.7 hi,  3.7 si,  0.0 st
%Cpu23 :  2.3 us, 19.0 sy,  0.0 ni, 78.3 id,  0.0 wa,  0.3 hi,  0.0 si,  0.0 st
MiB Mem :  64107.4 total,  46764.9 free,  11733.6 used,   5608.8 buff/cache
MiB Swap:  32248.0 total,  32248.0 free,      0.0 used.  51670.0 avail Mem

PID USER      PR   NI    VIRT    RES    SHR S  %CPU  %MEM     TIME+ COMMAND
213370 knot  20   0      34.0g   9.6g  41784 S 644.9  15.3   1319:12 /usr/sbin/knotd  

Thanks again for this great product.

Jonathan