Tech Blog / Security

CPU & Platform Security

CPU security issues are rarely “just patches.” They reshape scheduling, cache behavior, and syscall overhead. This guide focuses on practical impact: what changes in production, what metrics reveal it, and how to validate risk and cost without wasting days.

Read the guide Quick checklist
Focus Mitigations & trade-offs
Metrics p95 / p99 latency
Method Reproducible testing

Why CPU security feels “invisible” until it hurts

Many platform vulnerabilities exploit subtle interactions: speculation, caching, privilege boundaries, or isolation gaps. The fix often changes low-level behavior that only becomes obvious under sustained pressure: higher tail latency, increased context switching, or reduced throughput stability.

That’s why you can patch and think “nothing happened” — until production workload shifts and the system becomes less predictable.

Mitigation types and what they usually affect

Microcode updates

Fast to deploy, but rarely the full story. Expect changes in speculation behavior and edge-case performance on branch-heavy or syscall-heavy workloads.

Kernel / OS changes

Often where the real overhead lives: scheduling changes, isolation layers, syscall paths, and memory management decisions.

Compiler hardening

Can improve safety but shift costs into instruction count and cache pressure. Watch build flags and library versions for regressions.

What to measure (so you don’t lie to yourself)

Averages are comforting and often useless. Security overhead tends to appear in tails. Prioritize p95/p99 latency, sustained throughput stability, and error counters.

Rule: If your conclusion changes when you switch from avg → p95, your monitoring was incomplete.
  • p95/p99 latency under steady-state load, not bursts.
  • Context switching and scheduler contention signals.
  • I/O latency spikes during mixed workload pressure.
  • Thermal/power behavior (throttling changes after updates happen).

Quick checklist

Before patching

Record baseline p95/p99 under sustained load.

Note BIOS settings + microcode + kernel version.

Freeze workload mix for fair comparison.

After patching

Compare tails first, averages last.

Check regression signals: spikes + stalls + errors.

Correlate changes with deploys/config to avoid false blame.

“Security improves only when you can verify it.”