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Yuchung Cheng authored
If RTT is not available because Karn's check has failed or no new packet is acked, use the RTT measured from SACK to estimate the RTO. The sender can continue to estimate the RTO during loss recovery or reordering event upon receiving non-partial ACKs. This also changes when the RTO is re-armed. Previously it is only re-armed when some data is cummulatively acknowledged (i.e., SND.UNA advances), but now it is re-armed whenever RTT estimator is updated. This feature is particularly useful to reduce spurious timeout for buffer bloat including cellular carriers [1], and RTT estimation on reordering events. [1] "An In-depth Study of LTE: Effect of Network Protocol and Application Behavior on Performance", In Proc. of SIGCOMM 2013 Signed-off-by:
Yuchung Cheng <ycheng@google.com> Acked-by:
Neal Cardwell <ncardwell@google.com> Signed-off-by:
David S. Miller <davem@davemloft.net>
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