Windows Server 2012 R2 – tcpip.sys DPC latency spikes degrade throughput – Fix and Prevention

📖 ~1 min read

Table of contents

1. Symptom & Impact
2. Environment & Reproduction
3. Root Cause Analysis
4. Quick Triage
5. Step-by-Step Diagnosis
6. Solution — Primary Fix
7. Solution — Alternative Approaches
8. Verification & Acceptance Criteria
9. Rollback Plan
10. Prevention & Hardening
11. Related Errors & Cross-Refs
12. References & Further Reading

Symptom & Impact

Throughput drops and retransmits increase under load.

Environment & Reproduction

Observed on multi-NIC hosts with mixed offload settings.

Get-NetAdapterChecksumOffload
Get-NetAdapterLso

Root Cause Analysis

Offload conflicts drive elevated DPC processing.

Quick Triage

Measure processor DPC time and adapter settings.

Step-by-Step Diagnosis

Toggle offloads one by one to isolate culprit.

Solution — Primary Fix

Disable unstable offloads and update driver branch.

Disable-NetAdapterLso -Name 'Ethernet'
Restart-NetAdapter -Name 'Ethernet'

Solution — Alternative Approaches

Route latency-sensitive traffic to dedicated adapters.

Verification & Acceptance Criteria

DPC and retransmit counters return to baseline.

Rollback Plan

Restore previous advanced adapter property set.

Prevention & Hardening

Standardize offload profiles and audit quarterly.

Related Errors & Cross-Refs

Related to NDIS filter conflicts and VMQ drops.

Related tutorial: View the step-by-step tutorial for Windows Server 2012 R2.

View all Windows Server 2012 R2 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

Windows network performance tuning references.