Playback of tcpdump spins

[Stewart Smith]

I am glad to find the tool with a new version, but still leave a problem.
when I playback a size of 5GB tcpdump file , the tools is not stable. In MySQL, we can find that the QPS and TPS suddenly drop to zero after playbacking a some time. I find when have no QPS and TPS, the CPU usage of sys is higher than usual.
Use the tool "perf top", I find the spin_lock is higher than usual.

appearance：
samples pcnt function

9753.00 31.8% _spin_lock

so is it a bug?

wait for your answer, thanks

[lx (ffdlx718)]

HI, we have found the reason caused the problem in file named inet_hashtables.c. The function __inet_check_established caused spin_lock.

We modify /etc/sysctl.conf, add:

net.ipv4.tcp_syncookies = 1
net.ipv4.tcp_tw_reuse = 1
net.ipv4.tcp_tw_recycle = 1
net.ipv4.tcp_fin_timeout = 30

Now we can playback the tcpdump file continuously.

thank you very much for your reply.
Now we are testing the great playback tool.

PS: the tcpdump-mode fast may not work so effective in our experiments.

[Johannes Rudolph (johannes-rudolph)]

lx, seems we have run into the same problem as well. Could you share a bit more information of what you have analyzed and why you think modifying those settings helped?