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75 lines
2.9 KiB
Markdown
75 lines
2.9 KiB
Markdown
# eBPF sockops Example
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## Performance Optimization using eBPF sockops
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Network connections are essentially communication between sockets. eBPF provides a [bpf_msg_redirect_hash](https://man7.org/linux/man-pages/man7/bpf-helpers.7.html) function, which allows packets sent by applications to be directly forwarded to the destination socket, greatly accelerating the packet processing flow in the kernel.
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Here, sock_map is the crucial part that records socket rules, i.e., based on the current packet information, a socket connection is selected from sock_map to forward the request. Therefore, it is necessary to save the socket information to sock_map at the hook of sockops or elsewhere, and provide a key-based rule (generally a four-tuple) to find the socket.
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The Merbridge project uses eBPF instead of iptables to accelerate Istio. After using Merbridge (eBPF) optimization, inbound and outbound traffic will bypass many kernel modules, significantly improving performance, as shown in the figure below:
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## Running the Example
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This example program redirects traffic from the sender's socket (outbound) to the receiver's socket (inbound), **bypassing the TCP/IP kernel network stack**. In this example, we assume that the sender and receiver are running on the **same machine**.
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### Compiling the eBPF Program
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```shell
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# Compile the bpf_sockops program
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clang -O2 -g -Wall -target bpf -c bpf_sockops.c -o bpf_sockops.o
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clang -O2 -g -Wall -target bpf -c bpf_redir.c -o bpf_redir.o
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```
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### Loading the eBPF Program
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```shell
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sudo ./load.sh
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```
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You can use the [bpftool utility](https://github.com/torvalds/linux/blob/master/tools/bpf/bpftool/Documentation/bpftool-prog.rst) to check if these two eBPF programs have been loaded.
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```console
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$ sudo bpftool prog show
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63: sock_ops name bpf_sockmap tag 275467be1d69253d gpl
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loaded_at 2019-01-24T13:07:17+0200 uid 0
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xlated 1232B jited 750B memlock 4096B map_ids 58
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64: sk_msg name bpf_redir tag bc78074aa9dd96f4 gpl
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loaded_at 2019-01-24T13:07:17+0200 uid 0
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xlated 304B jited 233B memlock 4096B map_ids 58
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```
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### Running the [iperf3](https://iperf.fr/) Server
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```shell
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iperf3 -s -p 10000
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```
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### Running the [iperf3](https://iperf.fr/) Client
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```shell
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iperf3 -c 127.0.0.1 -t 10 -l 64k -p 10000
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```
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### Collecting Traces
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```console
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$ ./trace.sh
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iperf3-9516 [001] .... 22500.634108: 0: <<< ipv4 op = 4, port 18583 --> 4135
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iperf3-9516 [001] ..s1 22500.634137: 0: <<< ipv4 op = 5, port 4135 --> 18583
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iperf3-9516 [001] .... 22500.634523: 0: <<< ipv4 op = 4, port 19095 --> 4135
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iperf3-9516 [001] ..s1 22500.634536: 0: <<< ipv4 op = 5, port 4135 --> 19095
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```
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You should be able to see 4 events for socket establishment. If you don't see any events, the eBPF program may not have been attached correctly.
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### Unloading the eBPF Program
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```shell
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sudo ./unload.sh
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```
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## References
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- <https://github.com/zachidan/ebpf-sockops>- <https://github.com/merbridge/merbridge> |