use ntpperf

[folkertdev]

https://github.com/mlichvar/ntpperf

[folkertdev]

results (commit 4c7b060)

               |          responses            |        response time (ns)
rate   clients |  lost invalid   basic  xleave |    min    mean     max    rms
1000       100   0.00%   0.00% 100.00%   0.00%    +9888  +15296  +64832  15529
1500       150   0.00%   0.00% 100.00%   0.00%    +9617  +15823  +67099  16138
2250       225   0.00%   0.00% 100.00%   0.00%    +9247  +15214  +49618  15477
3375       337   0.00%   0.00% 100.00%   0.00%   +10508  +15244  +29252  15477
5062       506   0.00%   0.00% 100.00%   0.00%    +9468  +15321  +62264  15586
7593       759   0.00%   0.00% 100.00%   0.00%    +5721  +14583  +48321  14886
11389     1138   0.00%   0.00% 100.00%   0.00%    +4739  +14250  +44333  14588
17083     1708   0.00%   0.00% 100.00%   0.00%    +3096  +13368 +156704  14039
25624     2562   0.00%   0.00% 100.00%   0.00%    +2946  +14948 +149440  15994
38436     3843   0.00%   0.00% 100.00%   0.00%    +2845  +17903 +255960  19896
57654     5765   0.00%   0.00% 100.00%   0.00%    +3006  +19117 +133070  21276
86481     8648   0.00%   0.00% 100.00%   0.00%    +1553   +8495  +93305   9382
129721   12972   0.00%   0.00% 100.00%   0.00%    +1582  +11867 +182312  13587
194581   16384   0.00%   0.00% 100.00%   0.00%    +1603  +17988 +154750  20351
291871   16384  12.26%   0.00%  87.74%   0.00%  +205736 +276610 +483527 277192
437806   16384  42.95%   0.00%  57.05%   0.00%  +208923 +298836 +528392 299694
656709   16384  60.97%   0.00%  39.03%   0.00%  +194808 +298264 +576138 299458

[folkertdev]

and with NTS

               |          responses            |        response time (ns)
rate   clients |  lost invalid   basic  xleave |    min    mean     max    rms
1000       100   0.00%   0.00% 100.00%   0.00%    +7004  +15154 +138650  17087
1500       150   0.00%   0.00% 100.00%   0.00%    +7003  +20018 +172894  20709
2250       225   0.00%   0.00% 100.00%   0.00%   +12894  +19268  +63850  19679
3375       337   0.00%   0.00% 100.00%   0.00%    +6582  +19624  +61204  20347
5062       506   0.00%   0.00% 100.00%   0.00%    +5029  +18691  +61966  19623
7593       759   0.00%   0.00% 100.00%   0.00%    +4559  +17457 +212939  18414
11389     1138   0.00%   0.00% 100.00%   0.00%    +5059  +20753 +104265  21660
17083     1708   0.00%   0.00% 100.00%   0.00%    +3777  +18128  +98224  20830
25624     2562   0.00%   0.00% 100.00%   0.00%    +3286   +9932 +393426  12116
38436     3843   0.00%   0.00% 100.00%   0.00%    +3567  +10953  +93375  12295
57654     5765   0.00%   0.00% 100.00%   0.00%    +3577  +14766  +74479  16848
86481     8648   0.00%   0.00% 100.00%   0.00%    +3216  +20233 +192781  23235
129721   12972   0.00%   0.00% 100.00%   0.00%    +3536  +34001 +397004  39017
194581   16384  26.87%   0.00%  73.13%   0.00%  +394248 +514395 +780432 515200
291871   16384  51.68%   0.00%  48.32%   0.00%  +404839 +538324 +831297 539552

[cikzh]

Related to #1521