Summary:
Experiment with using adaptive thresholds for detecting packet losses through reordering or timeouts. When transportSettings.useAdaptiveLossThresholds is set to true, every time a spurious loss is detected, the thresholds will be updated to avoid marking similar packets as losses. In cases with a high degree of packet reordering, this improves bandwidth utilization significantly.
The useAdaptiveLossThresholds setting can be set using a new transport knob.
This was verified by transferring a 5 MB object across 50 Mbps link with high random packet reordering (emulated using netem)
```
+ tc -s qdisc replace dev veth7 root handle 1:0 netem rate 50Mbit limit 1250
+ tc -s qdisc add dev veth7 parent 1:0 handle 2: netem delay 15ms 5ms distribution normal limit 1250
```
Without adaptive thresholds, ~43% of sent bytes are retransmissions. Goodput is 2 Mbps.
With adaptive thresholds, ~3% of sent bytes are retransmissions. Goodput is ~17.5 Mbps.
Reviewed By: mjoras
Differential Revision: D33354584
fbshipit-source-id: 390bfb3398d499fcdf97a5cfd5654da3eeabed17
Summary:
Providers observers with insight into ACKs received. Works for both client and server transport.
Attempts to prevent wasted memory by removing any allocated memory for ACK events if no packets in flight. In tandem, reduces allocs by _not_ removing allocated memory when packets are in flight (as this means more ACK events will occur soon...).
Reviewed By: jbeshay
Differential Revision: D31221280
fbshipit-source-id: 64b73aa74c757ebbfc27bb9c2a047d08dc7a77ca
Summary:
Currently the `packetsWritten` observer event is only triggered when ACK-eliciting packets are written to the network. This change makes it so that the event is triggered even when non ACK-eliciting packets are written. In addition, this change increases the information provided in the observer event to reduce the processing that must be performed by observers.
More specifically, this diff makes the following changes:
- It creates two new structs — `WriteEvent` and `PacketsWrittenEvent` — and makes `PacketsWrittenEvent` and `AppLimitedEvent` inherit from `WriteEvent`, which contains the base set of fields that appear in both derived events. The base set of fields includes `writeCount` and the reference to the list of `OutstandingPackets`.
- A `PacketsWrittenEvent` is generated after each write loop during which packets are written.
- The `PacketsWrittenEvent` records the total number of packets written (the sum of ACK-eliciting and non ACK-eliciting packets written) and the total number of ACK-eliciting packets written during the last loop. By exposing this information, observers can determine whether there is value in inspecting the list of `OutstandingPackets` before doing so.
- In the future, I'll extend this event to also report the number of stream bytes written.
- It adopts a new builder pattern for observer events to make it easier to create instances of these structures:
- We use this approach instead of aggregate initialization (specifically designated initializers via aggregate initialization), because designated initializers (C++20 feature, although supported by some compilers long before) is not yet supported on all platforms for which we need this code to compile.
- I intend to change the other observer events to use this pattern as the number of arguments in some of their constructors makes them increasingly difficult to deal with.
Reviewed By: mjoras
Differential Revision: D31216724
fbshipit-source-id: 42ceb922d46ab0e0dc356f8726c2d0467a219587
Summary: Provide observers with visibility into stream events triggered by local and peer (e.g., new stream opened locally or by peer).
Reviewed By: mjoras
Differential Revision: D31886978
fbshipit-source-id: 7556fef0f336bd0f190b4474f1a7b0120aae6ef1
Summary:
Previously we were using a single flag appDataSentEvents to enable 3 callbacks
(startWritingFromAppLimited, packetsWritten and appRateLimited). This commit
creates separate flags to enable each of these callbacks, we have use-cases
where Observers might want only packetsWritten events and not the others.
Also, this commit refactors the logic to deliver these 3 callbacks to all
observers into a separate method so they can be unit tested easily.
Reviewed By: bschlinker
Differential Revision: D27925011
fbshipit-source-id: 7f7436dfc3d50c3abcb8ec121b221d20e30b0c4b
Summary:
Previously, we only had support for notifying observers when a QUIC socket
became application rate limited.
This change adds a similar notification when a socket does not become
application rate limited, i.e when the application *starts* writing data to the
socket - either for the first time on a newly established socket or after a
previous block of writes were written and the app had no more to write.
In addition, we include the number of outstanding packets (only those that are
carrying app data in them) so that observers can use this data to timestamp the
start and end of periods where the socket performs app data writes.
Reviewed By: yangchi
Differential Revision: D26559598
fbshipit-source-id: 0a8df7082b83e2ffad9b5addceca29cc03897243
Summary: Extend the Observer to record events for all knob frame received.
Reviewed By: bschlinker
Differential Revision: D26325312
fbshipit-source-id: 810589d08be3614c8c091cccb7bb9fbdb5c65402
Summary:
Extended instrumentationObserver to record packets that were spuriously lost due to reordering or timeout.
Depends on https://github.com/facebookincubator/mvfst/issues/185
Pull Request resolved: https://github.com/facebookincubator/mvfst/pull/186
Test Plan:
buck test //quic/api/test/...
buck test //quic/loss/test/...
buck test //quic/state/test/...
Proxygen canary on ELB and FLB
Reviewed By: bschlinker
Differential Revision: D24072374
Pulled By: sridharsrinivasan86
fbshipit-source-id: 2a22eeae7eb5c1bab405e8c5b7f4b96dff5afb59
Summary:
Given the large number of callbacks that are being triggered from the Observer
this change makes it possible to enable through a simple config, just the
subset of callbacks that a consumer is interested in receiving.
Observer and Socket Lifecycle callbacks are enabled by default, they are not
configurable.
Reviewed By: bschlinker
Differential Revision: D25879382
fbshipit-source-id: abe79ed92e958ddc96475c347f8ec7204400cdfa
Summary:
As titled. This is t he final diff that comples the migration to a unified
Observer interface.
Reviewed By: bschlinker
Differential Revision: D25850627
fbshipit-source-id: a9b9d83a6f6d0ba17d2aac8dbf3bacf74c8e16cb
Summary:
We were using the LifecycleObserver and InstrumentationObserver classes
separately, to generate and receive callbacks.
This change migrates both these to use the unified Observer callback class and
adjusts the unit tests.
Reviewed By: bschlinker
Differential Revision: D25845845
fbshipit-source-id: c489400f5d70bccadbcc1d957136c5ade36b65ff
Summary:
Here, we introduce a new Observer class that is a container for all the
callbacks that the QUIC Socket layer will invoke when interesting events happen
during the lifetime of the socket.
This class contains a union of all callbacks that are present in the
LifecycleObserver and InstrumentationObserver classes.
This is done in an effort to merge both the callback classes into one,
for easier maintainability. LifecycleObserver and InstrumentationObserver
are left behind temporarily, they will be deprecated in a future diff (up the stack).
Reviewed By: bschlinker
Differential Revision: D25845835
fbshipit-source-id: 425c865146ca061063cf6e463f8da92395f119f2
Summary: Inform LifecycleObservers when an EventBase is attached or detached from a QuicSocket.
Reviewed By: bschlinker
Differential Revision: D24294254
fbshipit-source-id: a606ad5ae4d4cbe3095e6ae32d6c74713325ad08
Summary:
This adds two events that we care mostly about d6d's perf: detecting blackhole
and detecting upperbound.
Reviewed By: bschlinker
Differential Revision: D23972141
fbshipit-source-id: bb6db6d1548ecddc9b255149e04a4c4844e9ec54
Summary:
Giving more access to the current state of the connection by exposing the socket.
Pull Request resolved: https://github.com/facebookincubator/mvfst/pull/185
Reviewed By: yangchi
Differential Revision: D23924861
Pulled By: bschlinker
fbshipit-source-id: 16866a93e58b6544e25d474a51ca17fab9ffdc55
Summary:
Due to high number of RTT samples I refactored the OutstandingPacket to
split the packet data and packet metrics. We know have access to metrics
without the need of saving the packet data.
Pull Request resolved: https://github.com/facebookincubator/mvfst/pull/178
Reviewed By: mjoras
Differential Revision: D23711641
Pulled By: bschlinker
fbshipit-source-id: 53791f1f6f6e184f37afca991a873af05909fbd2
Summary:
`InstrumentationObserver` is owned by `QuicSocket` now. However, to capture packet loss signal, we need it in `QuicConnectionState`. So, I refactored the code a little bit to make this easy. Changes in this code:
(a) Moved the definition of `InstrumentationObserver` and `LifeCycleObserver` to
a separate header `Observer.h`.
(b) Moved the vector of `InstrumentationObserver`s from `QuicSocket` to `QuicConnectionState`.
(c) Added a callback in `conn->pendingCallbacks` when a packet loss is detected
Reviewed By: bschlinker
Differential Revision: D23018569
fbshipit-source-id: e70d954839bdb70679ecd52d2bd1a6a6841f6778
