From: Eric Dumazet <eric.duma...@gmail.com> Date: Wed, 07 Sep 2016 14:49:28 -0700
> From: Yaogong Wang <wygi...@google.com> > > Over the years, TCP BDP has increased by several orders of magnitude, > and some people are considering to reach the 2 Gbytes limit. > > Even with current window scale limit of 14, ~1 Gbytes maps to ~740,000 > MSS. > > In presence of packet losses (or reorders), TCP stores incoming packets > into an out of order queue, and number of skbs sitting there waiting for > the missing packets to be received can be in the 10^5 range. > > Most packets are appended to the tail of this queue, and when > packets can finally be transferred to receive queue, we scan the queue > from its head. > > However, in presence of heavy losses, we might have to find an arbitrary > point in this queue, involving a linear scan for every incoming packet, > throwing away cpu caches. > > This patch converts it to a RB tree, to get bounded latencies. > > Yaogong wrote a preliminary patch about 2 years ago. > Eric did the rebase, added ofo_last_skb cache, polishing and tests. > > Tested with network dropping between 1 and 10 % packets, with good > success (about 30 % increase of throughput in stress tests) > > Next step would be to also use an RB tree for the write queue at sender > side ;) > > Signed-off-by: Yaogong Wang <wygi...@google.com> > Signed-off-by: Eric Dumazet <eduma...@google.com> The sooner this gets applied the sooner it gets tested and any remaining bugs discovered and fixed. Applied, thanks Eric.
