Stop your eBPF kprobes from dumping massive amounts of noise into dmesg

Technical Briefing | 7/30/2026

You probably started playing with eBPF to trace a specific kernel function, maybe something around network queuing or file descriptors. You wrote a simple kprobe, attached it, and watched your terminal light up with thousands of events per second. It works until you check your system logs and realize you just flooded the kernel ring buffer, potentially dropping actual error messages in the process. It’s a classic rookie mistake that ruins your production logs.

Why printing to the trace pipe is a trap

The default way people output data from eBPF is via bpf_trace_printk. It is convenient for local debugging, but it writes directly to the global trace pipe. This is shared across the entire kernel. If your probe triggers on a hot path, you are effectively performing a denial-of-service on your own observability pipeline. The kernel is fast, but it’s not fast enough to handle thousands of print calls without context switching and locking overhead.

bpftool prog show name your_program_name
bpftool map show pinned /sys/fs/bpf/your_map_name
cat /sys/kernel/debug/tracing/trace_pipe | head -n 20

Shift to perf buffers or ring buffers

• Use bpf_perf_event_output for passing data to userspace instead of printk
• Keep the eBPF program logic lean to minimize execution time per probe
• Implement circular buffers in userspace to handle spikes without blocking the kernel

The right approach is to treat your eBPF program as a data producer and let a userspace daemon handle the formatting and storage. If you really need to debug in real-time without the overhead, pipe your output to a dedicated perf ring buffer. It isolates your noise from the rest of the kernel’s critical messages. Next time your logs are missing that one vital disk error, look at your instrumentation before you blame the hardware.