[Bloat] Thoughts on Stochastic Fair Blue

[Jonathan Morton]

On 24 Mar, 2011, at 3:44 pm, Dave Taht wrote:

>> Here is the POC patch I am currently testing, with a probability to
>> "early drop" a packet of one percent per ms (HZ=1000 here), only if
>> packet stayed at least 4 ms on queue.

A fixed time threshold doesn't take into account the wildly varying bandwidths of connections.  For example, 4ms will cause almost any queued packet on a 33.6K modem uplink (or a 3G or GSM tether) to be marked, yet with the 128-packet default size for SFQ, a GigE NIC will typically empty the queue before any packets reach the marking threshold.

But perhaps a heuristic such as not marking packets which are the last in their bucket would be okay, and mark everything else when the queue is more than half full.

 - Jonathan