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
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