This file describes how to run the tcp_*_kern.o tcp_bpf (or socket_ops)
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programs. These programs attach to a cgroupv2. The following commands create
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a cgroupv2 and attach a bash shell to the group.
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mkdir -p /tmp/cgroupv2
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mount -t cgroup2 none /tmp/cgroupv2
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mkdir -p /tmp/cgroupv2/foo
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bash
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echo $$ >> /tmp/cgroupv2/foo/cgroup.procs
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Anything that runs under this shell belongs to the foo cgroupv2. To load
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(attach) one of the tcp_*_kern.o programs:
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bpftool prog load tcp_basertt_kern.o /sys/fs/bpf/tcp_prog
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bpftool cgroup attach /tmp/cgroupv2/foo sock_ops pinned /sys/fs/bpf/tcp_prog
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bpftool prog tracelog
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"bpftool prog tracelog" will continue to run printing the BPF log buffer.
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The tcp_*_kern.o programs use special print functions to print logging
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information (if enabled by the ifdef).
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If using netperf/netserver to create traffic, you need to run them under the
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cgroupv2 to which the BPF programs are attached (i.e. under bash shell
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attached to the cgroupv2).
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To remove (unattach) a socket_ops BPF program from a cgroupv2:
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bpftool cgroup detach /tmp/cgroupv2/foo sock_ops pinned /sys/fs/bpf/tcp_prog
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