Commit Overhead vs Throughput
Commit Overhead vs Throughput
Analysis of commit protocol overhead as percentage of total transaction time.
Overhead = (commit_latency / total_latency) × 100
This represents time spent in retries, exponential backoff, and manifest I/O.
Values shown as mean ± standard deviation across seeds.
real_conflict_probability = 0.0
| Throughput (c/s) | Success Rate (%) | Mean Overhead (%) | P50 Overhead (%) | P95 Overhead (%) | P99 Overhead (%) |
|---|---|---|---|---|---|
| 0.2 ± 0.0 | 100.0 ± 0.0 | 0.4 ± 0.0 | 0.4 ± 0.0 | 0.6 ± 0.0 | 0.7 ± 0.0 |
| 0.5 ± 0.0 | 100.0 ± 0.0 | 0.8 ± 0.0 | 0.8 ± 0.0 | 1.1 ± 0.0 | 1.2 ± 0.1 |
| 1.0 ± 0.0 | 100.0 ± 0.0 | 1.5 ± 0.0 | 1.5 ± 0.0 | 1.8 ± 0.0 | 2.0 ± 0.1 |
| 1.9 ± 0.0 | 100.0 ± 0.0 | 2.8 ± 0.0 | 2.8 ± 0.0 | 3.3 ± 0.0 | 3.5 ± 0.0 |
| 4.8 ± 0.1 | 98.0 ± 0.2 | 6.9 ± 0.1 | 6.9 ± 0.1 | 7.6 ± 0.1 | 7.9 ± 0.1 |
| 7.8 ± 0.0 | 78.8 ± 0.3 | 11.1 ± 0.1 | 11.0 ± 0.1 | 11.7 ± 0.1 | 12.0 ± 0.1 |
| 9.4 ± 0.0 | 47.5 ± 0.2 | 13.4 ± 0.0 | 13.3 ± 0.0 | 13.8 ± 0.0 | 14.2 ± 0.0 |
| 10.7 ± 0.0 | 21.3 ± 0.1 | 15.2 ± 0.0 | 15.1 ± 0.0 | 15.6 ± 0.0 | 15.8 ± 0.0 |
| 11.5 ± 0.0 | 11.2 ± 0.0 | 16.3 ± 0.0 | 16.3 ± 0.0 | 16.7 ± 0.0 | 16.9 ± 0.0 |
real_conflict_probability = 0.1
| Throughput (c/s) | Success Rate (%) | Mean Overhead (%) | P50 Overhead (%) | P95 Overhead (%) | P99 Overhead (%) |
|---|---|---|---|---|---|
| 0.2 ± 0.0 | 100.0 ± 0.0 | 0.4 ± 0.0 | 0.4 ± 0.0 | 0.7 ± 0.0 | 1.1 ± 0.1 |
| 0.5 ± 0.0 | 100.0 ± 0.0 | 0.8 ± 0.0 | 0.8 ± 0.0 | 1.2 ± 0.0 | 1.6 ± 0.0 |
| 1.0 ± 0.0 | 100.0 ± 0.0 | 1.6 ± 0.0 | 1.5 ± 0.0 | 2.0 ± 0.1 | 2.4 ± 0.1 |
| 2.0 ± 0.0 | 100.0 ± 0.0 | 3.0 ± 0.0 | 2.9 ± 0.0 | 3.6 ± 0.0 | 4.1 ± 0.1 |
| 4.8 ± 0.1 | 97.6 ± 0.1 | 6.9 ± 0.1 | 6.8 ± 0.1 | 7.7 ± 0.1 | 8.4 ± 0.1 |
| 7.6 ± 0.1 | 77.0 ± 0.6 | 10.9 ± 0.1 | 10.8 ± 0.1 | 11.6 ± 0.1 | 12.3 ± 0.1 |
| 9.2 ± 0.0 | 46.3 ± 0.1 | 13.1 ± 0.0 | 13.1 ± 0.0 | 13.9 ± 0.0 | 14.4 ± 0.0 |
| 10.5 ± 0.0 | 20.8 ± 0.0 | 14.9 ± 0.0 | 14.9 ± 0.0 | 15.6 ± 0.0 | 16.0 ± 0.0 |
| 11.3 ± 0.0 | 10.9 ± 0.0 | 16.1 ± 0.0 | 16.0 ± 0.0 | 16.7 ± 0.0 | 17.1 ± 0.0 |
real_conflict_probability = 0.3
| Throughput (c/s) | Success Rate (%) | Mean Overhead (%) | P50 Overhead (%) | P95 Overhead (%) | P99 Overhead (%) |
|---|---|---|---|---|---|
| 0.2 ± 0.0 | 100.0 ± 0.0 | 0.5 ± 0.0 | 0.4 ± 0.0 | 1.0 ± 0.0 | 1.4 ± 0.1 |
| 0.5 ± 0.0 | 100.0 ± 0.0 | 0.9 ± 0.0 | 0.8 ± 0.0 | 1.5 ± 0.1 | 1.9 ± 0.0 |
| 1.0 ± 0.0 | 100.0 ± 0.0 | 1.6 ± 0.0 | 1.5 ± 0.0 | 2.3 ± 0.0 | 2.8 ± 0.1 |
| 2.0 ± 0.0 | 100.0 ± 0.0 | 3.1 ± 0.0 | 2.9 ± 0.0 | 3.9 ± 0.0 | 4.6 ± 0.1 |
| 4.7 ± 0.1 | 95.3 ± 0.3 | 7.0 ± 0.1 | 6.9 ± 0.1 | 8.2 ± 0.1 | 9.1 ± 0.1 |
| 7.1 ± 0.0 | 72.0 ± 0.4 | 10.4 ± 0.0 | 10.3 ± 0.0 | 11.5 ± 0.0 | 12.4 ± 0.0 |
| 8.7 ± 0.0 | 43.7 ± 0.1 | 12.6 ± 0.0 | 12.5 ± 0.0 | 13.6 ± 0.0 | 14.3 ± 0.0 |
| 10.0 ± 0.0 | 19.9 ± 0.0 | 14.5 ± 0.0 | 14.4 ± 0.0 | 15.4 ± 0.0 | 16.0 ± 0.0 |
| 10.8 ± 0.0 | 10.4 ± 0.0 | 15.6 ± 0.0 | 15.4 ± 0.0 | 16.4 ± 0.0 | 16.9 ± 0.0 |
real_conflict_probability = 0.5
| Throughput (c/s) | Success Rate (%) | Mean Overhead (%) | P50 Overhead (%) | P95 Overhead (%) | P99 Overhead (%) |
|---|---|---|---|---|---|
| 0.2 ± 0.0 | 100.0 ± 0.0 | 0.6 ± 0.0 | 0.5 ± 0.0 | 1.1 ± 0.0 | 1.5 ± 0.1 |
| 0.5 ± 0.0 | 100.0 ± 0.0 | 1.0 ± 0.0 | 0.9 ± 0.0 | 1.7 ± 0.0 | 2.1 ± 0.1 |
| 1.0 ± 0.0 | 100.0 ± 0.0 | 1.7 ± 0.0 | 1.6 ± 0.0 | 2.5 ± 0.1 | 3.2 ± 0.1 |
| 2.0 ± 0.0 | 99.9 ± 0.1 | 3.2 ± 0.1 | 3.0 ± 0.1 | 4.2 ± 0.0 | 5.0 ± 0.1 |
| 4.5 ± 0.0 | 92.1 ± 0.4 | 7.0 ± 0.1 | 6.8 ± 0.1 | 8.3 ± 0.1 | 9.5 ± 0.1 |
| 6.5 ± 0.0 | 66.4 ± 0.4 | 9.8 ± 0.0 | 9.7 ± 0.0 | 11.2 ± 0.0 | 12.2 ± 0.0 |
| 8.0 ± 0.0 | 40.4 ± 0.1 | 11.9 ± 0.0 | 11.8 ± 0.0 | 13.2 ± 0.0 | 14.0 ± 0.0 |
| 9.4 ± 0.0 | 18.7 ± 0.0 | 13.9 ± 0.0 | 13.8 ± 0.0 | 15.0 ± 0.0 | 15.6 ± 0.0 |
| 10.2 ± 0.0 | 9.9 ± 0.0 | 15.0 ± 0.0 | 14.9 ± 0.0 | 16.0 ± 0.0 | 16.6 ± 0.0 |
Interpretation
- Low overhead (<10%): System operating efficiently, minimal contention
- Medium overhead (10-30%): Moderate contention, acceptable performance
- High overhead (30-50%): High contention, commit protocol becoming significant
- Very high overhead (>50%): Commit protocol dominates, system saturated
Values shown as mean ± standard deviation across multiple seeds. At saturation, overhead can exceed 50%, meaning more time is spent retrying commits than executing transactions!