feat: auto-tune stream receive window #1868
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This commit adds a basic smoke test using the `test-ficture` simulator, asserting that on a connection with unlimited bandwidth and 50ms round-trip-time Neqo can eventually achieve > 1 Gbit/s throughput. Showcases the potential a future stream flow-control auto-tuning algorithm can have. See mozilla#733.
Previously the stream send and receive window had a hard limit at 1MB. On high latency and/or high bandwidth connections, 1 MB is not enough to exhaust the available bandwidth. Sample scenario: ``` delay_s = 0.05 window_bits = 1 * 1024 * 1024 * 8 bandwidth_bits_s = window_bits / delay_s bandwidth_mbits_s = bandwidth_bits_s / 1024 / 1024 # 160.0 ``` In other words, on a 50 ms connection a 1 MB window can at most achieve 160 Mbit/s. This commit introduces an auto-tuning algorithm for the stream receive window, increasing the window towards the bandwidth-delay product of the connection.
Failed Interop TestsQUIC Interop Runner, client vs. server, differences relative to 9143d73. neqo-latest as client
neqo-latest as server
All resultsSucceeded Interop TestsQUIC Interop Runner, client vs. server neqo-latest as client
neqo-latest as server
Unsupported Interop TestsQUIC Interop Runner, client vs. server neqo-latest as client
neqo-latest as server
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This commit adds a basic smoke test using the `test-fixture` simulator, asserting the expected bandwidth on a 1 gbit link. Given mozilla#733, the current expected bandwidth is limited by the fixed sized stream receive buffer (1MiB).
A `Node` (e.g. a `Client`, `Server` or `TailDrop` router) can be in 3 states:
``` rust
enum NodeState {
/// The node just produced a datagram. It should be activated again as soon as possible.
Active,
/// The node is waiting.
Waiting(Instant),
/// The node became idle.
Idle,
}
```
`NodeHolder::ready()` determines whether a `Node` is ready to be processed
again. When `NodeState::Waiting`, it should only be ready when `t <= now`, i.e.
the waiting time has passed, not `t >= now`.
``` rust
impl NodeHolder {
fn ready(&self, now: Instant) -> bool {
match self.state {
Active => true,
Waiting(t) => t <= now, // not >=
Idle => false,
}
}
}
```
The previous behavior lead to wastefull non-ready `Node`s being processed and
thus a large test runtime when e.g. simulating a gbit
connection (mozilla#2203).
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Previously the stream send and receive window had a hard limit at 1MB. On high latency and/or high bandwidth connections (i.e. large bandwidth-delay product), 1 MB is not enough to exhaust the available bandwidth.
Sample scenario:
In other words, on a 50 ms connection a 1 MB window can at most achieve 160 Mbit/s.
This commit introduces an auto-tuning algorithm for the stream receive window, increasing the window towards the bandwidth-delay product of the connection.
Work in progress for now. Able to transfer >160Mbit/s on a 50ms link already.
Currently implementing the algorithm proposed in #733 (comment). I still have to familiarize myself with the algorithm proposed in #733 (comment). Which ever is chosen, both need the same scaffolding.
Fixes #733.
TODO