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Rebase to master. |
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LPardue
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Implements Hystart++ based on IETF draft: https://tools.ietf.org/html/draft-balasubramanian-tcpm-hystartplusplus-02 HyStart++ is an improved version of original Hystart. It can be used with Reno and CUBIC (or possibly other loss based congestion control). It's enabled by default. You can disable it by calling config API provided. Config APIs: - C: quiche_config_set_hystart() - Rust: Config.set_hystart() API Changes: - CongestionControlOps API: `epoch`` is added to on_packet_acked() and congestion_event() Tools Update: - tools/apps/quiche-{client,server}: added --disable-hystart command line option Different from TCP: TCP implementation uses sequence number to check a start of the round. In QUIC, current implementation uses packet number instead. However packet number space is unique per epoch but Initial and Handshake epoch is short, so only applies HyStart++ to Application epoch. In TCP, sequence number is reused for retransmitted packets but QUIC will use a new packet number for retransmit so this is not exactly same. But it should be fine because this is only for the slow start episode and when QUIC connection sees a packet loss, it enters into recovery episode and exits from slow start, so retransmitted packet number is not used during HyStart++ slow start.
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@ghedo let me know if there is additional comments/work needed. I rebased to master again today. |
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Sorry for the delay @junhochoi I added a couple of suggestions that I can merge manually, I still think we can probably improve the internal API a bit, but we can do it later so there's no point in delaying this further.
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Cool. Thanks! |
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Note that it's based on #475 since this PR includes changes for CUBIC as well.
Implements Hystart++ based on IETF draft:
https://tools.ietf.org/html/draft-balasubramanian-tcpm-hystartplusplus-02
HyStart++ is an improved version of original Hystart. It can be used
with Reno and CUBIC (or possibly other loss based congestion control).
It's enabled by default. You can disable it by calling config API provided.
Config APIs:
API Changes:
epochis added to on_packet_acked()and congestion_event()
Tools Update:
command line option
Different from TCP: TCP implementation uses sequence number to
check a start of the round. In QUIC, current implementation uses
packet number instead. However packet number space is unique
per epoch but Initial and Handshake epoch is short, so only
applies HyStart++ to Application epoch.
In TCP, sequence number is reused for retransmitted packets
but QUIC will use a new packet number for retransmit so
this is not exactly same. But it should be fine because this is
only for the slow start episode and when QUIC connection sees a
packet loss, it enters into recovery episode and exits from slow
start, so retransmitted packet number is not used during HyStart++
slow start.