Stop eBPF from blinding you with massive syscall events

Technical Briefing | 7/27/2026

Most eBPF guides treat every event as a precious snowflake, but if you run a tracer on a high-throughput box, you’ll melt your CPU before you get a single useful insight. I once tried to trace every openat call on a production database node, and I watched the system load climb toward infinity while the agent struggled to shove everything into the ring buffer. That’s a rookie mistake that’ll take down your host faster than a memory leak.

Why the ring buffer is your new enemy

The standard approach for tracers is to copy everything to user space for processing. That context switch is expensive, and when your application is hammering syscalls, your tracing buffer becomes a bottleneck. You need to push the logic down into the kernel. If you can filter the noise in BPF C code before it ever touches user space, you save yourself the performance hit and keep the logs clean.

bpftrace -e 'tracepoint:syscalls:sys_enter_openat /pid == 1234/ { printf("%s %d\n", comm, pid); }'

• Filter by PID or UID in the BPF program, not in your analysis script
• Use maps to aggregate counters in the kernel instead of streaming events
• Keep your perf events per-CPU to avoid cross-core locking contention
• Watch your drop counts in /sys/kernel/debug/tracing/buffer_size_kb

If you really need to see everything, you aren’t doing observability, you’re doing a denial of service attack on yourself. Set your filters early, use perf_event_output sparingly, and never trust a trace that hasn’t been scoped to a specific process or namespace. When your boss asks why the monitoring agent is eating 20 percent of the CPU, being able to point to a specific, scoped probe is the difference between a quick fix and a post-mortem.