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samples/bpf: add sample program that periodically dumps TCP stats
Uses new RTT callback to dump stats every second.
$ mkdir -p /tmp/cgroupv2
$ mount -t cgroup2 none /tmp/cgroupv2
$ mkdir -p /tmp/cgroupv2/foo
$ echo $$ >> /tmp/cgroupv2/foo/cgroup.procs
$ bpftool prog load ./tcp_dumpstats_kern.o /sys/fs/bpf/tcp_prog
$ bpftool cgroup attach /tmp/cgroupv2/foo sock_ops pinned /sys/fs/bpf/tcp_prog
$ bpftool prog tracelog
$ # run neper/netperf/etc
Used neper to compare performance with and without this program attached
and didn't see any noticeable performance impact.
Sample output:
<idle>-0 [015] ..s. 2074.128800: 0: dsack_dups=0 delivered=242526
<idle>-0 [015] ..s. 2074.128808: 0: delivered_ce=0 icsk_retransmits=0
<idle>-0 [015] ..s. 2075.130133: 0: dsack_dups=0 delivered=323599
<idle>-0 [015] ..s. 2075.130138: 0: delivered_ce=0 icsk_retransmits=0
<idle>-0 [005] .Ns. 2076.131440: 0: dsack_dups=0 delivered=404648
<idle>-0 [005] .Ns. 2076.131447: 0: delivered_ce=0 icsk_retransmits=0
Cc: Eric Dumazet <edumazet@google.com>
Cc: Priyaranjan Jha <priyarjha@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Cc: Soheil Hassas Yeganeh <soheil@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Acked-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>