# RPC Pressure Evidence

This file records the current synthetic RPC responsiveness guard for
`aria2-rust-pro`.

## Scope

Current guard coverage is synthetic but no longer limited to a single
`tellStatus` loop:

- in-process dispatcher
- BT-like magnet workload
- repeated `aria2.tellStatus`
- sampled `aria2.getFiles`
- repeated `aria2.tellActive`
- repeated `aria2.tellGlobalStat`
- Criterion `rpc_mixed_pressure` and `bt_visibility_pressure` anchors

This is not a public-swarm benchmark. It is a deterministic regression guard
for scheduler/RPC responsiveness while the runtime is still approximation-heavy.

## Guard Tests

- `rpc_bt_pressure_guard_keeps_status_active_and_global_stat_responsive`
- `rpc_bt_mixed_pressure_guard_covers_churned_status_files_and_global_views`

Basic guard shape:

- 64 BT-like magnet tasks
- 4 pressure rounds
- 256 total `tellStatus` calls
- 4 `tellActive` calls
- 4 `tellGlobalStat` calls
- runtime tick updates injected during the loop to keep non-zero BT-like state

Mixed guard shape:

- 96 BT-like magnet tasks
- 6 pressure rounds
- 576 total `tellStatus` calls
- 72 sampled `getFiles` calls
- 6 `tellActive` calls
- 6 `tellGlobalStat` calls
- per-download runtime tick churn before every status probe

## Current Thresholds

These thresholds are deliberately broad. They are there to catch obvious
regressions, not to certify final performance:

- cumulative `tellStatus` time across the run: `<= 2000ms`
- cumulative `tellActive` time across the run: `<= 500ms`
- cumulative `tellGlobalStat` time across the run: `<= 500ms`
- cumulative mixed guard time across the run: `<= 4000ms`

## Current Criterion Anchors

Current focused Criterion runs on this host:

| Benchmark | Mean | 95% CI |
| --- | ---: | ---: |
| `rpc_mixed_pressure/mixed_rpc/96` | `92.383 us` | `90.867 .. 93.895 us` |
| `rpc_mixed_pressure/mixed_rpc/192` | `175.169 us` | `160.464 .. 192.884 us` |
| `bt_visibility_pressure/bt_visibility/32` | `2.3293 ms` | `1.0756 .. 4.0986 ms` |
| `bt_visibility_pressure/bt_visibility/64` | `2.1302 ms` | `2.0707 .. 2.2057 ms` |

Interpretation:

- the deterministic integration tests now cover mixed BT/RPC status, file, and
  global-stat surfaces under runtime churn
- the Criterion anchors give a current non-HTTP performance regression guard
- the thresholds remain intentionally broad so host-local noise does not turn a
  synthetic guard into a flaky gate

## Next Steps

Further work should extend this guard with:

- explicit scheduler tick pressure
- resource counters suitable for later perf reporting
- a documented comparison against the C++ reference once comparable benchmark
  suites exist