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 | 0.3 ± 0.0 | 0.3 ± 0.0 | 0.5 ± 0.0 | 0.6 ± 0.1 |
| 0.5 ± 0.0 | 100.0 ± 0.0 | 0.7 ± 0.0 | 0.7 ± 0.0 | 1.0 ± 0.0 | 1.1 ± 0.1 |
| 1.0 ± 0.0 | 100.0 ± 0.0 | 1.4 ± 0.0 | 1.4 ± 0.0 | 1.7 ± 0.0 | 1.9 ± 0.1 |
| 1.9 ± 0.0 | 100.0 ± 0.0 | 2.8 ± 0.0 | 2.7 ± 0.0 | 3.1 ± 0.1 | 3.4 ± 0.1 |
| 4.9 ± 0.1 | 100.0 ± 0.0 | 6.9 ± 0.1 | 6.9 ± 0.1 | 7.4 ± 0.2 | 7.7 ± 0.2 |
| 9.9 ± 0.1 | 100.0 ± 0.0 | 13.7 ± 0.1 | 13.7 ± 0.1 | 14.4 ± 0.2 | 14.8 ± 0.2 |
| 19.7 ± 0.1 | 100.0 ± 0.0 | 27.2 ± 0.1 | 27.2 ± 0.2 | 28.2 ± 0.1 | 28.6 ± 0.2 |
| 33.4 ± 0.0 | 67.8 ± 0.1 | 46.3 ± 0.0 | 46.2 ± 0.0 | 46.6 ± 0.0 | 46.8 ± 0.0 |
| 36.4 ± 0.0 | 36.1 ± 0.0 | 50.3 ± 0.0 | 50.2 ± 0.0 | 50.5 ± 0.0 | 50.6 ± 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 | 0.3 ± 0.0 | 0.3 ± 0.0 | 0.6 ± 0.0 | 0.9 ± 0.2 |
| 0.5 ± 0.0 | 100.0 ± 0.0 | 0.7 ± 0.0 | 0.7 ± 0.0 | 1.1 ± 0.1 | 1.4 ± 0.1 |
| 1.0 ± 0.0 | 100.0 ± 0.0 | 1.5 ± 0.0 | 1.4 ± 0.0 | 1.9 ± 0.0 | 2.2 ± 0.1 |
| 2.0 ± 0.0 | 100.0 ± 0.0 | 2.8 ± 0.0 | 2.8 ± 0.0 | 3.3 ± 0.0 | 3.7 ± 0.0 |
| 4.9 ± 0.1 | 100.0 ± 0.0 | 6.9 ± 0.1 | 6.9 ± 0.1 | 7.6 ± 0.1 | 8.0 ± 0.1 |
| 9.9 ± 0.1 | 100.0 ± 0.0 | 13.8 ± 0.2 | 13.8 ± 0.2 | 14.6 ± 0.1 | 15.2 ± 0.1 |
| 19.7 ± 0.1 | 99.9 ± 0.0 | 27.4 ± 0.1 | 27.4 ± 0.1 | 28.3 ± 0.2 | 28.9 ± 0.2 |
| 32.7 ± 0.1 | 66.0 ± 0.1 | 45.4 ± 0.0 | 45.3 ± 0.0 | 46.0 ± 0.0 | 46.3 ± 0.0 |
| 35.6 ± 0.0 | 35.3 ± 0.1 | 49.4 ± 0.0 | 49.4 ± 0.0 | 50.0 ± 0.0 | 50.3 ± 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 | 0.3 ± 0.0 | 0.3 ± 0.0 | 0.8 ± 0.0 | 1.2 ± 0.1 |
| 0.5 ± 0.0 | 100.0 ± 0.0 | 0.8 ± 0.0 | 0.8 ± 0.0 | 1.4 ± 0.0 | 1.7 ± 0.1 |
| 1.0 ± 0.0 | 100.0 ± 0.0 | 1.5 ± 0.0 | 1.5 ± 0.0 | 2.1 ± 0.1 | 2.5 ± 0.1 |
| 2.0 ± 0.0 | 100.0 ± 0.0 | 2.9 ± 0.0 | 2.8 ± 0.0 | 3.5 ± 0.0 | 4.0 ± 0.1 |
| 4.9 ± 0.0 | 100.0 ± 0.0 | 7.1 ± 0.1 | 7.0 ± 0.1 | 7.9 ± 0.1 | 8.5 ± 0.1 |
| 9.8 ± 0.1 | 100.0 ± 0.0 | 13.9 ± 0.1 | 13.8 ± 0.1 | 14.9 ± 0.1 | 15.6 ± 0.1 |
| 19.6 ± 0.1 | 99.5 ± 0.0 | 27.5 ± 0.1 | 27.4 ± 0.1 | 28.6 ± 0.1 | 29.4 ± 0.1 |
| 31.1 ± 0.0 | 62.6 ± 0.1 | 43.4 ± 0.0 | 43.3 ± 0.0 | 44.3 ± 0.0 | 44.9 ± 0.0 |
| 34.0 ± 0.0 | 33.6 ± 0.0 | 47.6 ± 0.0 | 47.5 ± 0.0 | 48.4 ± 0.0 | 48.8 ± 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 | 0.4 ± 0.0 | 0.3 ± 0.0 | 1.0 ± 0.1 | 1.3 ± 0.1 |
| 0.5 ± 0.0 | 100.0 ± 0.0 | 0.8 ± 0.0 | 0.8 ± 0.0 | 1.5 ± 0.1 | 1.8 ± 0.1 |
| 1.0 ± 0.0 | 100.0 ± 0.0 | 1.6 ± 0.0 | 1.5 ± 0.0 | 2.3 ± 0.1 | 2.7 ± 0.1 |
| 2.0 ± 0.0 | 100.0 ± 0.0 | 3.0 ± 0.1 | 2.9 ± 0.1 | 3.7 ± 0.1 | 4.2 ± 0.1 |
| 4.9 ± 0.0 | 100.0 ± 0.0 | 7.2 ± 0.1 | 7.1 ± 0.1 | 8.2 ± 0.1 | 8.8 ± 0.1 |
| 9.9 ± 0.1 | 100.0 ± 0.0 | 14.1 ± 0.1 | 14.0 ± 0.1 | 15.3 ± 0.1 | 16.1 ± 0.1 |
| 19.4 ± 0.1 | 98.5 ± 0.0 | 27.5 ± 0.1 | 27.4 ± 0.1 | 29.0 ± 0.2 | 29.9 ± 0.2 |
| 29.2 ± 0.0 | 59.0 ± 0.1 | 41.1 ± 0.0 | 41.0 ± 0.0 | 42.3 ± 0.0 | 43.0 ± 0.0 |
| 32.2 ± 0.0 | 31.7 ± 0.1 | 45.3 ± 0.0 | 45.2 ± 0.0 | 46.4 ± 0.0 | 46.9 ± 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!