Part 1:
Change bandwidth estimate to exponential moving average
(Similar to Westwood+ Simple Bandwidth Estimator in streaming)
instead of 40 ms bucket.
Also use it for tunnel.participatingBandwidthOut stat.
Remove linear moving average code previously used for stat
Reduce RED threshold from 120% to 95% of limit
Part 2:
Fix the other part of RED which is the dropping calculation.
Previously, it simply used the bandwidth to start dropping if
it was higher than a threshold. The drop percentage rose from
0 to 100%, linearly, based on how far the bandwidth was
above the threshold. This was far, far from the RED paper.
Now, we follow the RED paper (see ref. in SyntheticREDQueue javadoc)
to calculate an average queue size, using the exact same
exponential moving average method used for bandwidth.
Similar to CoDel, it also includes a count of how long
the size is over the threshold, and increases the drop probability with the count.
The unadjusted drop probability rises from 0 to 2%
and then everything is dropped, as in the RED paper.
The low and high thresholds are configured at 77 ms and 333 ms of queued data, respectively.
The queue is "synthetic" in that there's not actually a queue.
It only calculates how big the queue would be if it were
a real queue and were being emptied at exactly the target rate.
The actual queueing is done downstream in the transports and in UDP-Sender.
The goals are, for an 80% default share, to do most of the
part. traffic dropping here in RED, not downstream in UDP-Sender,
while fully utilizing the configured share bandwidth.
If the router goes into high message delay mode, that means we are not dropping enough in RED.
Above 80% share this probably doesn't work as well.
There may be more tuning required, in particular to achieve the goal of "protecting" the UDP-Sender
queue and local client/router traffic by dropping more aggressively in RED.
This patch also improves the overhead estimate for outbound part. tunnel traffic at the OBEP.
Reviewed, tested, acked by zlatinb
Have SocketTimeout interrupt thread
Cancel SocketTimeout and use soTImeout after reading headers if able
Cancel SocketTimeout in finally
Cleanups and javadocs
Ensure IPv4/v6 peer tests are alternated
Reschedule peer test if result is UNKNOWN and a state transition is pending
Fix peer test last send time not being set in all cases
We want the part. traffic RED dropper to have some effect
and not let traffic back up at the router bandwidth
limiter and into the UDP-Sender queue,
as it removes any room for client and router traffic,
and throws the router into high message delay mode.
Increase min and max queue size
Tweak stats
Util: Allow creation of CoDel queues with non-default parameters
New params are tentative, may be adjusted later
