Description of problem:
intermittently congestion stats are not printed in tcpcong

Version-Release number of selected component (if applicable):

[root@localhost ~]# rpm -qa | grep bcc
bcc-tools-0.25.0-2.el9.x86_64
bcc-0.25.0-2.el9.x86_64
python3-bcc-0.25.0-2.el9.noarch
How reproducible:

I have started iperf3 for 60 sec as below:

[root@localhost ~]# iperf3 -c 192.168.122.163 -t 60
Connecting to host 192.168.122.163, port 5201
[ 5] local 192.168.122.207 port 47186 connected to 192.168.122.163 port 5201
[ ID] Interval Transfer Bitrate Retr Cwnd
[ 5] 0.00-1.00 sec 235 MBytes 1.97 Gbits/sec 70 1.68 MBytes
[ 5] 1.00-2.00 sec 190 MBytes 1.60 Gbits/sec 0 1.85 MBytes
[ 5] 2.00-3.00 sec 191 MBytes 1.60 Gbits/sec 0 2.00 MBytes
[ 5] 3.00-4.00 sec 208 MBytes 1.74 Gbits/sec 0 2.11 MBytes
[ 5] 4.00-5.00 sec 244 MBytes 2.05 Gbits/sec 0 2.20 MBytes
[ 5] 5.00-6.00 sec 175 MBytes 1.47 Gbits/sec 140 1.63 MBytes
[ 5] 6.00-7.00 sec 186 MBytes 1.56 Gbits/sec 162 1.22 MBytes
[ 5] 7.00-8.00 sec 190 MBytes 1.59 Gbits/sec 0 1.29 MBytes
[ 5] 8.00-9.00 sec 244 MBytes 2.04 Gbits/sec 0 1.35 MBytes
[ 5] 9.00-10.00 sec 201 MBytes 1.69 Gbits/sec 0 1.38 MBytes
[ 5] 10.00-11.00 sec 138 MBytes 1.15 Gbits/sec 0 1.45 MBytes
[ 5] 11.00-12.00 sec 145 MBytes 1.22 Gbits/sec 0 1.52 MBytes
[ 5] 12.00-13.00 sec 144 MBytes 1.21 Gbits/sec 0 1.59 MBytes
[ 5] 13.00-14.00 sec 179 MBytes 1.50 Gbits/sec 0 1.62 MBytes
[ 5] 14.00-15.00 sec 119 MBytes 993 Mbits/sec 0 1.67 MBytes
[ 5] 15.00-16.00 sec 212 MBytes 1.79 Gbits/sec 0 1.69 MBytes
[ 5] 16.00-17.00 sec 144 MBytes 1.20 Gbits/sec 0 1.73 MBytes
[ 5] 17.00-18.00 sec 228 MBytes 1.91 Gbits/sec 0 1.75 MBytes
[ 5] 18.00-19.00 sec 145 MBytes 1.22 Gbits/sec 0 1.81 MBytes
[ 5] 19.00-20.00 sec 165 MBytes 1.38 Gbits/sec 343 1.40 MBytes
[ 5] 20.00-21.00 sec 141 MBytes 1.18 Gbits/sec 0 1.52 MBytes
[ 5] 21.00-22.00 sec 168 MBytes 1.41 Gbits/sec 0 1.62 MBytes
[ 5] 22.00-23.00 sec 232 MBytes 1.95 Gbits/sec 0 1.69 MBytes
[ 5] 23.00-24.00 sec 234 MBytes 1.96 Gbits/sec 0 1.75 MBytes
[ 5] 24.00-25.00 sec 262 MBytes 2.20 Gbits/sec 0 1.78 MBytes
[ 5] 25.00-26.00 sec 248 MBytes 2.08 Gbits/sec 0 1.80 MBytes
[ 5] 26.00-27.00 sec 215 MBytes 1.80 Gbits/sec 0 1.82 MBytes
[ 5] 27.00-28.00 sec 255 MBytes 2.15 Gbits/sec 0 1.82 MBytes
[ 5] 28.00-29.00 sec 102 MBytes 860 Mbits/sec 0 1.82 MBytes
[ 5] 29.00-30.00 sec 105 MBytes 881 Mbits/sec 0 1.82 MBytes
[ 5] 30.00-31.00 sec 218 MBytes 1.82 Gbits/sec 0 1.82 MBytes
[ 5] 31.00-32.00 sec 226 MBytes 1.90 Gbits/sec 0 1.83 MBytes
[ 5] 32.00-33.00 sec 238 MBytes 1.98 Gbits/sec 32 1.41 MBytes
[ 5] 33.00-34.00 sec 232 MBytes 1.95 Gbits/sec 0 1.52 MBytes
[ 5] 34.00-35.00 sec 119 MBytes 1.00 Gbits/sec 0 1.63 MBytes
[ 5] 35.00-36.00 sec 135 MBytes 1.13 Gbits/sec 208 1.21 MBytes
[ 5] 36.00-37.00 sec 204 MBytes 1.71 Gbits/sec 0 1.29 MBytes
[ 5] 37.00-38.00 sec 234 MBytes 1.96 Gbits/sec 0 1.34 MBytes
[ 5] 38.00-39.00 sec 131 MBytes 1.10 Gbits/sec 0 1.39 MBytes
[ 5] 39.00-40.00 sec 140 MBytes 1.17 Gbits/sec 0 1.41 MBytes
[ 5] 40.00-41.00 sec 135 MBytes 1.13 Gbits/sec 0 1.43 MBytes
[ 5] 41.00-42.00 sec 234 MBytes 1.96 Gbits/sec 0 1.45 MBytes
[ 5] 42.00-43.00 sec 150 MBytes 1.26 Gbits/sec 0 1.50 MBytes
[ 5] 43.00-44.00 sec 225 MBytes 1.88 Gbits/sec 0 1.52 MBytes
[ 5] 44.00-45.00 sec 159 MBytes 1.34 Gbits/sec 0 1.56 MBytes
[ 5] 45.00-46.00 sec 226 MBytes 1.90 Gbits/sec 0 1.59 MBytes
[ 5] 46.00-47.00 sec 109 MBytes 912 Mbits/sec 0 1.64 MBytes
[ 5] 47.00-48.00 sec 205 MBytes 1.72 Gbits/sec 204 1.25 MBytes
[ 5] 48.00-49.00 sec 212 MBytes 1.78 Gbits/sec 0 1.37 MBytes
[ 5] 49.00-50.00 sec 232 MBytes 1.95 Gbits/sec 0 1.46 MBytes
[ 5] 50.00-51.00 sec 204 MBytes 1.70 Gbits/sec 0 1.53 MBytes
[ 5] 51.00-52.00 sec 250 MBytes 2.10 Gbits/sec 0 1.59 MBytes
[ 5] 52.00-53.00 sec 182 MBytes 1.54 Gbits/sec 0 1.62 MBytes
[ 5] 53.00-54.00 sec 241 MBytes 2.02 Gbits/sec 0 1.64 MBytes
[ 5] 54.00-55.00 sec 198 MBytes 1.66 Gbits/sec 0 1.65 MBytes
[ 5] 55.00-56.00 sec 108 MBytes 902 Mbits/sec 0 1.66 MBytes
[ 5] 56.00-57.01 sec 231 MBytes 1.93 Gbits/sec 0 1.66 MBytes
[ 5] 57.01-58.00 sec 242 MBytes 2.04 Gbits/sec 0 1.66 MBytes
[ 5] 58.00-59.00 sec 222 MBytes 1.87 Gbits/sec 0 1.66 MBytes
[ 5] 59.00-60.00 sec 145 MBytes 1.22 Gbits/sec 0 1.67 MBytes

• - - - - - - - - - - - - - - - - - - - - - - - -
  [ ID] Interval Transfer Bitrate Retr
  [ 5] 0.00-60.00 sec 11.2 GBytes 1.60 Gbits/sec 1159 sender
  [ 5] 0.00-60.05 sec 11.2 GBytes 1.60 Gbits/sec receiver

iperf Done.

During these, I have started tcpcong with 5 sec duration

1. /usr/share/bcc/tools/tcpcong 5
   ..
   ..
   15:14:44

15:14:49
LAddrPort RAddrPort Open_ms Dod_ms Rcov_ms Cwr_ms Los_ms Chgs
192.168.122.207/47186 192.168.122.163/5201 0 0 7 0 0 1

15:14:54
LAddrPort RAddrPort Open_ms Dod_ms Rcov_ms Cwr_ms Los_ms Chgs
192.168.122.207/47186 192.168.122.163/5201 921 0 31 0 0 3

15:14:59 <<--- just timestamp printed

15:15:04 <<--- along timestamp, column headers are printed but not the stats
LAddrPort RAddrPort Open_ms Dod_ms Rcov_ms Cwr_ms Los_ms Chgs

15:15:09
LAddrPort RAddrPort Open_ms Dod_ms Rcov_ms Cwr_ms Los_ms Chgs
192.168.122.207/47186 192.168.122.163/5201 0 0 6 0 0 1

15:15:14 <<--- just timestamp printed

15:15:19 <<--- along timestamp, column headers are printed but not the stats
LAddrPort RAddrPort Open_ms Dod_ms Rcov_ms Cwr_ms Los_ms Chgs

15:15:24
LAddrPort RAddrPort Open_ms Dod_ms Rcov_ms Cwr_ms Los_ms Chgs
192.168.122.207/47186 192.168.122.163/5201 3595 0 16 0 0 3

15:15:29 <<--- along timestamp, column headers are printed but not the stats
LAddrPort RAddrPort Open_ms Dod_ms Rcov_ms Cwr_ms Los_ms Chgs

15:15:34 <<--- along timestamp, column headers are printed but not the stats
LAddrPort RAddrPort Open_ms Dod_ms Rcov_ms Cwr_ms Los_ms Chgs

15:15:39
LAddrPort RAddrPort Open_ms Dod_ms Rcov_ms Cwr_ms Los_ms Chgs
192.168.122.207/47186 192.168.122.163/5201 0 0 5 0 0 1

15:15:44 <<--- along timestamp, column headers are printed but not the stats
LAddrPort RAddrPort Open_ms Dod_ms Rcov_ms Cwr_ms Los_ms Chgs

15:15:49

Actual results:

Intermittently look like stats were missed

Expected results:

I feel it should print the stats for every sample, If I am wrong in my assumption can you please help me understand the behavior for:

• "just timestamp printed"
• "along timestamp, column headers are printed but not the stats"

Additional info: