November 28, 2025
Fast vibes, zero graphs
How to use Linux vsock for fast VM communication
Dev touts 'fast' VM chat—commenters yell 'benchmarks or it didn't happen'
TLDR: A tutorial shows VMs talking to their host via vsock, using gRPC and Bazel for a simple add-two-numbers service. Commenters demanded benchmarks and questioned whether gRPC’s overhead nullifies any speed gains, with some preferring a simpler explainer—making performance proof the real headline.
A developer showed how to make a virtual machine (a sandboxed computer) chat with its host using vsock, a direct pipe that skips normal internet plumbing. The demo uses gRPC (Google’s Remote Procedure Call) and Bazel (a build tool) to spin up a tiny service that adds two numbers—clean, clever, and allegedly “fast.” But the crowd? Oh, they brought popcorn. The loudest chorus was: Where are the numbers? One user roasted the post for hyping speed without a single benchmark. Another fired back that gRPC and Protobuf (the message format) are so slow that the socket type isn’t even the bottleneck—basically, changing the road won’t help if your car is a tractor. Others said the tooling flex (Bazel! gRPC!) muddied the lesson; they wanted a simple vsock explainer and dropped a more approachable read: this article. The security-minded lurkers nodded: vsock keeps traffic local to the machine, which can be neat. But meme energy took over: “Fast because it only does 2+2,” “benchmarks or bust,” and “moving your service to another box = new headaches.” Verdict: cool concept, solid demo, but without graphs, the community isn’t buying the speed claims.
Key Points
- •The article demonstrates VM–host communication using Linux vsock, avoiding TCP/IP and network virtualization.
- •A simple gRPC service (Addition RPC) runs inside a VM, with vsock used as the transport mechanism.
- •Bazel is used for reproducible builds, with dependencies: rules_proto, rules_cc, Protobuf (com_google_protobuf), and gRPC.
- •Bazel targets proto_library, cc_proto_library, and cc_grpc_library generate the required C++ Protobuf and gRPC code.
- •The server is built as a statically linked C++ binary (cc_binary) to simplify deployment into the VM.