Re: [PATCH v6 net-next 2/2] tcp: Add Redundant Data Bundling (RDB)

Rick Jones
2016-03-15T01:04:16Z

On 03/14/2016 02:15 PM, Eric Dumazet wrote:
> On Thu, 2016-03-03 at 19:06 +0100, Bendik Rønning Opstad wrote:
>> Redundant Data Bundling (RDB) is a mechanism for TCP aimed at reducing
>> the latency for applications sending time-dependent data.
>>
>> Latency-sensitive applications or services, such as online games,
>> remote control systems, and VoIP, produce traffic with thin-stream
>> characteristics, characterized by small packets and relatively high
>> inter-transmission times (ITT). When experiencing packet loss, such
>> latency-sensitive applications are heavily penalized by the need to
>> retransmit lost packets, which increases the latency by a minimum of
>> one RTT for the lost packet. Packets coming after a lost packet are
>> held back due to head-of-line blocking, causing increased delays for
>> all data segments until the lost packet has been retransmitted.
>
> Acked-by: Eric Dumazet <edumazet@google.com>
>
> Note that RDB probably should get some SNMP counters,
> so that we get an idea of how many times a loss could be repaired.

And some idea of the duplication seen by receivers, assuming there isn't
already a counter for such a thing in Linux.

happy benchmarking,

rick jones

>
> Ideally, if the path happens to be lossless, all these pro active
> bundles are overhead. Might be useful to make RDB conditional to
> tp->total_retrans or something.
>
>