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 | 0.3 ± 0.0 | 0.6 ± 0.0 | 0.7 ± 0.0 |
| 0.5 ± 0.0 | 100.0 ± 0.0 | 0.8 ± 0.0 | 0.7 ± 0.0 | 1.0 ± 0.0 | 1.1 ± 0.1 |
| 1.0 ± 0.0 | 100.0 ± 0.0 | 1.5 ± 0.0 | 1.4 ± 0.0 | 1.8 ± 0.0 | 2.0 ± 0.0 |
| 2.0 ± 0.1 | 100.0 ± 0.0 | 2.9 ± 0.1 | 2.8 ± 0.1 | 3.3 ± 0.1 | 3.6 ± 0.1 |
| 5.0 ± 0.0 | 100.0 ± 0.0 | 7.0 ± 0.1 | 6.9 ± 0.0 | 7.5 ± 0.1 | 7.9 ± 0.1 |
| 9.9 ± 0.1 | 100.0 ± 0.0 | 13.8 ± 0.0 | 13.8 ± 0.0 | 14.6 ± 0.2 | 15.0 ± 0.2 |
| 18.9 ± 0.1 | 95.4 ± 0.2 | 26.2 ± 0.1 | 26.2 ± 0.1 | 27.0 ± 0.1 | 27.3 ± 0.1 |
| 26.1 ± 0.0 | 52.4 ± 0.1 | 36.2 ± 0.0 | 36.2 ± 0.0 | 36.6 ± 0.0 | 36.8 ± 0.1 |
| 28.3 ± 0.0 | 27.8 ± 0.1 | 39.3 ± 0.0 | 39.3 ± 0.0 | 39.6 ± 0.0 | 39.7 ± 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 | 1.5 ± 0.0 | 1.4 ± 0.0 | 2.0 ± 0.1 | 2.4 ± 0.1 |
| 2.0 ± 0.0 | 100.0 ± 0.0 | 2.9 ± 0.1 | 2.9 ± 0.1 | 3.5 ± 0.1 | 3.9 ± 0.1 |
| 4.9 ± 0.1 | 100.0 ± 0.0 | 7.0 ± 0.1 | 7.0 ± 0.1 | 7.8 ± 0.1 | 8.3 ± 0.1 |
| 9.9 ± 0.1 | 99.9 ± 0.0 | 13.9 ± 0.1 | 13.8 ± 0.0 | 14.8 ± 0.1 | 15.4 ± 0.2 |
| 18.2 ± 0.1 | 91.9 ± 0.3 | 25.5 ± 0.1 | 25.4 ± 0.1 | 26.4 ± 0.1 | 26.9 ± 0.1 |
| 25.0 ± 0.0 | 50.2 ± 0.1 | 34.9 ± 0.0 | 34.8 ± 0.0 | 35.5 ± 0.0 | 35.9 ± 0.0 |
| 27.4 ± 0.0 | 26.9 ± 0.0 | 38.2 ± 0.0 | 38.1 ± 0.0 | 38.8 ± 0.0 | 39.2 ± 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 ± 0.1 | 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 ± 0.1 |
| 1.0 ± 0.0 | 100.0 ± 0.0 | 1.6 ± 0.1 | 1.5 ± 0.0 | 2.3 ± 0.1 | 2.8 ± 0.1 |
| 2.0 ± 0.0 | 100.0 ± 0.0 | 3.0 ± 0.1 | 2.9 ± 0.1 | 3.8 ± 0.1 | 4.4 ± 0.1 |
| 4.9 ± 0.1 | 100.0 ± 0.0 | 7.2 ± 0.1 | 7.1 ± 0.1 | 8.2 ± 0.1 | 9.0 ± 0.2 |
| 9.8 ± 0.1 | 99.2 ± 0.1 | 14.0 ± 0.1 | 13.9 ± 0.1 | 15.3 ± 0.1 | 16.1 ± 0.1 |
| 16.6 ± 0.1 | 84.2 ± 0.2 | 23.6 ± 0.1 | 23.5 ± 0.1 | 24.9 ± 0.1 | 25.7 ± 0.1 |
| 22.6 ± 0.0 | 45.4 ± 0.1 | 31.9 ± 0.0 | 31.8 ± 0.0 | 33.0 ± 0.0 | 33.6 ± 0.0 |
| 25.4 ± 0.0 | 24.8 ± 0.1 | 35.7 ± 0.0 | 35.6 ± 0.0 | 36.6 ± 0.0 | 37.1 ± 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 | 0.5 ± 0.0 | 0.4 ± 0.0 | 1.1 ± 0.1 | 1.5 ± 0.2 |
| 0.5 ± 0.0 | 100.0 ± 0.0 | 1.0 ± 0.0 | 0.9 ± 0.0 | 1.6 ± 0.0 | 2.0 ± 0.0 |
| 1.0 ± 0.0 | 100.0 ± 0.0 | 1.7 ± 0.0 | 1.6 ± 0.0 | 2.5 ± 0.1 | 3.1 ± 0.1 |
| 2.0 ± 0.0 | 100.0 ± 0.0 | 3.1 ± 0.1 | 3.0 ± 0.1 | 4.1 ± 0.1 | 4.7 ± 0.1 |
| 4.9 ± 0.1 | 99.9 ± 0.0 | 7.4 ± 0.1 | 7.2 ± 0.1 | 8.7 ± 0.1 | 9.7 ± 0.1 |
| 9.5 ± 0.0 | 96.4 ± 0.1 | 14.0 ± 0.0 | 13.8 ± 0.0 | 15.6 ± 0.1 | 16.7 ± 0.1 |
| 14.9 ± 0.0 | 75.2 ± 0.1 | 21.5 ± 0.1 | 21.2 ± 0.1 | 23.1 ± 0.1 | 24.0 ± 0.1 |
| 19.9 ± 0.0 | 39.8 ± 0.2 | 28.5 ± 0.0 | 28.3 ± 0.0 | 29.9 ± 0.0 | 30.6 ± 0.0 |
| 22.8 ± 0.0 | 22.3 ± 0.1 | 32.4 ± 0.0 | 32.3 ± 0.0 | 33.7 ± 0.0 | 34.4 ± 0.1 |
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!