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.
t_cas_mean = 15
| 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 | 0.8 ± 0.1 |
| 0.5 ± 0.0 | 100.0 ± 0.0 | 0.9 ± 0.0 | 0.8 ± 0.0 | 1.2 ± 0.1 | 1.4 ± 0.0 |
| 1.0 ± 0.0 | 100.0 ± 0.0 | 1.6 ± 0.0 | 1.5 ± 0.0 | 2.0 ± 0.0 | 2.3 ± 0.1 |
| 1.9 ± 0.0 | 100.0 ± 0.0 | 2.9 ± 0.0 | 2.9 ± 0.0 | 3.5 ± 0.0 | 3.8 ± 0.1 |
| 4.9 ± 0.1 | 99.8 ± 0.0 | 7.1 ± 0.1 | 7.1 ± 0.1 | 7.9 ± 0.1 | 8.3 ± 0.1 |
| 8.8 ± 0.1 | 88.8 ± 0.3 | 12.6 ± 0.1 | 12.5 ± 0.1 | 13.4 ± 0.1 | 13.9 ± 0.1 |
| 10.5 ± 0.0 | 53.2 ± 0.1 | 15.1 ± 0.0 | 15.0 ± 0.0 | 15.8 ± 0.0 | 16.2 ± 0.0 |
| 11.7 ± 0.0 | 23.3 ± 0.0 | 16.7 ± 0.0 | 16.6 ± 0.0 | 17.4 ± 0.0 | 17.7 ± 0.0 |
| 12.5 ± 0.0 | 12.1 ± 0.0 | 17.8 ± 0.0 | 17.8 ± 0.0 | 18.5 ± 0.0 | 18.8 ± 0.0 |
t_cas_mean = 50
| 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 | 0.6 ± 0.0 | 1.0 ± 0.1 | 1.3 ± 0.2 |
| 0.5 ± 0.0 | 100.0 ± 0.0 | 1.1 ± 0.1 | 1.0 ± 0.0 | 1.6 ± 0.1 | 2.0 ± 0.1 |
| 1.0 ± 0.0 | 100.0 ± 0.0 | 1.8 ± 0.0 | 1.7 ± 0.0 | 2.5 ± 0.0 | 2.9 ± 0.1 |
| 2.0 ± 0.0 | 100.0 ± 0.0 | 3.3 ± 0.0 | 3.2 ± 0.0 | 4.2 ± 0.0 | 4.8 ± 0.1 |
| 4.5 ± 0.0 | 91.0 ± 0.4 | 7.2 ± 0.0 | 7.0 ± 0.0 | 8.7 ± 0.0 | 9.6 ± 0.1 |
| 5.5 ± 0.0 | 55.7 ± 0.2 | 8.7 ± 0.0 | 8.5 ± 0.0 | 10.4 ± 0.0 | 11.2 ± 0.1 |
| 6.2 ± 0.0 | 31.2 ± 0.1 | 9.7 ± 0.0 | 9.5 ± 0.0 | 11.4 ± 0.0 | 12.2 ± 0.0 |
| 6.8 ± 0.0 | 13.4 ± 0.0 | 10.6 ± 0.0 | 10.4 ± 0.0 | 12.3 ± 0.0 | 12.9 ± 0.0 |
| 7.0 ± 0.0 | 6.7 ± 0.0 | 10.9 ± 0.0 | 10.7 ± 0.0 | 12.5 ± 0.0 | 13.2 ± 0.0 |
t_cas_mean = 100
| Throughput (c/s) | Success Rate (%) | Mean Overhead (%) | P50 Overhead (%) | P95 Overhead (%) | P99 Overhead (%) |
|---|
| 0.2 ± 0.0 | 100.0 ± 0.0 | 0.8 ± 0.0 | 0.8 ± 0.0 | 1.5 ± 0.0 | 1.8 ± 0.1 |
| 0.5 ± 0.0 | 100.0 ± 0.0 | 1.4 ± 0.0 | 1.3 ± 0.0 | 2.2 ± 0.1 | 2.9 ± 0.2 |
| 1.0 ± 0.0 | 100.0 ± 0.0 | 2.2 ± 0.0 | 2.1 ± 0.0 | 3.5 ± 0.1 | 4.4 ± 0.1 |
| 2.0 ± 0.0 | 99.1 ± 0.1 | 4.0 ± 0.1 | 3.7 ± 0.1 | 5.9 ± 0.1 | 7.5 ± 0.2 |
| 3.2 ± 0.0 | 64.7 ± 0.3 | 6.3 ± 0.0 | 5.9 ± 0.0 | 9.4 ± 0.0 | 10.8 ± 0.1 |
| 3.7 ± 0.0 | 37.4 ± 0.1 | 7.1 ± 0.0 | 6.7 ± 0.0 | 10.2 ± 0.1 | 11.5 ± 0.1 |
| 4.0 ± 0.0 | 20.2 ± 0.1 | 7.6 ± 0.0 | 7.3 ± 0.0 | 10.7 ± 0.1 | 12.0 ± 0.1 |
| 4.2 ± 0.0 | 8.3 ± 0.0 | 7.9 ± 0.0 | 7.6 ± 0.0 | 11.1 ± 0.0 | 12.3 ± 0.0 |
| 4.3 ± 0.0 | 4.1 ± 0.0 | 8.1 ± 0.0 | 7.7 ± 0.0 | 11.2 ± 0.0 | 12.4 ± 0.1 |
t_cas_mean = 200
| Throughput (c/s) | Success Rate (%) | Mean Overhead (%) | P50 Overhead (%) | P95 Overhead (%) | P99 Overhead (%) |
|---|
| 0.2 ± 0.0 | 100.0 ± 0.0 | 1.4 ± 0.0 | 1.3 ± 0.1 | 2.7 ± 0.0 | 3.6 ± 0.1 |
| 0.5 ± 0.0 | 100.0 ± 0.0 | 2.0 ± 0.1 | 1.8 ± 0.1 | 4.0 ± 0.2 | 5.6 ± 0.3 |
| 1.0 ± 0.0 | 99.7 ± 0.2 | 3.4 ± 0.1 | 2.9 ± 0.1 | 6.7 ± 0.2 | 9.1 ± 0.4 |
| 1.6 ± 0.0 | 82.9 ± 0.4 | 5.3 ± 0.0 | 4.6 ± 0.0 | 10.5 ± 0.1 | 13.3 ± 0.1 |
| 2.1 ± 0.0 | 41.1 ± 0.5 | 6.3 ± 0.0 | 5.6 ± 0.0 | 11.9 ± 0.2 | 14.3 ± 0.2 |
| 2.2 ± 0.0 | 22.3 ± 0.1 | 6.9 ± 0.0 | 6.2 ± 0.0 | 12.5 ± 0.1 | 14.8 ± 0.2 |
| 2.3 ± 0.0 | 11.5 ± 0.0 | 7.1 ± 0.0 | 6.4 ± 0.0 | 12.7 ± 0.1 | 14.8 ± 0.1 |
| 2.4 ± 0.0 | 4.8 ± 0.0 | 7.2 ± 0.0 | 6.6 ± 0.1 | 13.0 ± 0.1 | 15.1 ± 0.1 |
| 2.5 ± 0.0 | 2.4 ± 0.0 | 7.3 ± 0.0 | 6.7 ± 0.0 | 13.0 ± 0.1 | 15.1 ± 0.1 |
t_cas_mean = 500
| Throughput (c/s) | Success Rate (%) | Mean Overhead (%) | P50 Overhead (%) | P95 Overhead (%) | P99 Overhead (%) |
|---|
| 0.2 ± 0.0 | 100.0 ± 0.0 | 3.0 ± 0.1 | 2.6 ± 0.1 | 6.7 ± 0.3 | 9.6 ± 0.6 |
| 0.5 ± 0.0 | 98.8 ± 0.3 | 5.2 ± 0.2 | 4.2 ± 0.2 | 13.4 ± 0.9 | 19.4 ± 1.1 |
| 0.7 ± 0.0 | 74.3 ± 0.9 | 7.8 ± 0.1 | 6.2 ± 0.1 | 19.0 ± 0.4 | 24.2 ± 0.4 |
| 0.9 ± 0.0 | 44.0 ± 0.5 | 8.9 ± 0.2 | 7.3 ± 0.3 | 21.0 ± 0.5 | 25.3 ± 0.3 |
| 1.0 ± 0.0 | 19.7 ± 0.3 | 9.6 ± 0.1 | 8.2 ± 0.2 | 21.5 ± 0.3 | 25.9 ± 0.3 |
| 1.0 ± 0.0 | 10.1 ± 0.1 | 9.7 ± 0.1 | 8.3 ± 0.2 | 21.5 ± 0.4 | 26.0 ± 0.2 |
| 1.0 ± 0.0 | 5.1 ± 0.0 | 9.8 ± 0.4 | 8.4 ± 0.4 | 21.8 ± 0.9 | 25.7 ± 0.8 |
| 1.1 ± 0.0 | 2.1 ± 0.0 | 9.8 ± 0.1 | 8.4 ± 0.2 | 21.7 ± 0.1 | 25.8 ± 0.4 |
| 1.1 ± 0.0 | 1.1 ± 0.0 | 9.9 ± 0.2 | 8.5 ± 0.3 | 21.7 ± 0.7 | 25.8 ± 0.5 |
t_cas_mean = 1000
| Throughput (c/s) | Success Rate (%) | Mean Overhead (%) | P50 Overhead (%) | P95 Overhead (%) | P99 Overhead (%) |
|---|
| 0.2 ± 0.0 | 99.9 ± 0.1 | 6.4 ± 0.4 | 5.3 ± 0.5 | 16.1 ± 1.4 | 23.8 ± 2.9 |
| 0.4 ± 0.0 | 75.1 ± 1.4 | 12.3 ± 0.2 | 9.7 ± 0.3 | 31.3 ± 1.1 | 38.0 ± 0.8 |
| 0.4 ± 0.0 | 44.5 ± 0.4 | 14.3 ± 0.4 | 12.1 ± 0.4 | 33.1 ± 0.4 | 39.3 ± 0.8 |
| 0.5 ± 0.0 | 24.7 ± 0.3 | 15.2 ± 0.5 | 13.5 ± 0.6 | 34.0 ± 1.1 | 39.6 ± 0.4 |
| 0.5 ± 0.0 | 10.4 ± 0.1 | 15.3 ± 0.4 | 13.5 ± 0.5 | 33.8 ± 0.7 | 40.0 ± 0.8 |
| 0.5 ± 0.0 | 5.4 ± 0.1 | 15.4 ± 0.5 | 13.3 ± 0.5 | 34.4 ± 1.2 | 39.6 ± 0.7 |
| 0.5 ± 0.0 | 2.7 ± 0.0 | 15.6 ± 0.4 | 13.9 ± 0.6 | 34.4 ± 1.1 | 40.0 ± 0.7 |
| 0.6 ± 0.0 | 1.1 ± 0.0 | 15.2 ± 0.3 | 13.4 ± 0.5 | 33.8 ± 0.6 | 39.4 ± 0.6 |
| 0.6 ± 0.0 | 0.6 ± 0.0 | 15.4 ± 0.4 | 13.5 ± 0.6 | 34.2 ± 0.3 | 39.6 ± 0.8 |
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!
