tcp: Add congestion control support
tcp: Add congestion control support

This patch adds congestion control to our TCP according to RFC5681.
These four algorithms: slow start, congestion avoidance, fast
retransmit, and fast recovery, are added.

Reviewed-by: Pekka Enberg <add4fcd06328a394f0ad91feda7ee057316dc5ed@cloudius-systems.com>

leejir/seastar,phonkee/scylla,printedheart/seastar,acbellini/seastar,chunshengster/seastar,printedheart/seastar,glommer/scylla,kjniemi/seastar,stamhe/scylla,tempbottle/seastar,syuu1228/seastar,asias/scylla,jonathanleang/seastar,scylladb/seastar,shaunstanislaus/scylla,cloudius-systems/seastar,tempbottle/seastar,raphaelsc/scylla,slivne/seastar,raphaelsc/seastar,avikivity/scylla,bzero/seastar,bowlofstew/scylla,koolhazz/seastar,shyamalschandra/seastar,glommer/scylla,norcimo5/seastar,rluta/scylla,joerg84/seastar,joerg84/seastar,dreamsxin/seastar,syuu1228/seastar,aruanruan/scylla,acbellini/scylla,justintung/scylla,xtao/seastar,rentongzhang/scylla,hongliangzhao/seastar,gwicke/scylla,linearregression/seastar,bowlofstew/seastar,xtao/seastar,dwdm/scylla,koolhazz/seastar,victorbriz/scylla,stamhe/seastar,tempbottle/scylla,aruanruan/scylla,avikivity/scylla,capturePointer/scylla,acbellini/seastar,kjniemi/scylla,stamhe/scylla,glommer/scylla,printedheart/seastar,bowlofstew/scylla,sjperkins/seastar,stamhe/seastar,kangkot/scylla,senseb/scylla,rentongzhang/scylla,dreamsxin/seastar,avikivity/seastar,dwdm/seastar,anzihenry/seastar,raphaelsc/scylla,bzero/seastar,tempbottle/seastar,ducthangho/imdb,dwdm/scylla,cloudius-systems/seastar,anzihenry/seastar,victorbriz/scylla,capturePointer/scylla,shyamalschandra/seastar,guiquanz/scylla,guiquanz/scylla,leejir/seastar,mixja/seastar,kangkot/scylla,gwicke/scylla,dreamsxin/seastar,scylladb/scylla,wildinto/seastar,dwdm/seastar,shyamalschandra/seastar,cloudius-systems/seastar,phonkee/scylla,linearregression/scylla,jonathanleang/seastar,xtao/seastar,respu/scylla,slivne/seastar,victorbriz/scylla,shaunstanislaus/scylla,rluta/scylla,linearregression/seastar,ducthangho/imdb,capturePointer/scylla,rluta/scylla,kjniemi/scylla,tempbottle/scylla,acbellini/scylla,kangkot/scylla,raphaelsc/scylla,acbellini/seastar,scylladb/seastar,norcimo5/seastar,chunshengster/seastar,joerg84/seastar,wildinto/seastar,tempbottle/scylla,raphaelsc/seastar,avikivity/seastar,duarten/scylla,shaunstanislaus/scylla,flashbuckets/seastar,respu/scylla,flashbuckets/seastar,scylladb/scylla-seastar,linearregression/scylla,hongliangzhao/seastar,avikivity/scylla,chunshengster/seastar,wildinto/scylla,dwdm/seastar,asias/scylla,eklitzke/scylla,wildinto/seastar,scylladb/seastar,stamhe/scylla,flashbuckets/seastar,jonathanleang/seastar,aruanruan/scylla,mixja/seastar,scylladb/scylla-seastar,scylladb/scylla-seastar,duarten/scylla,bowlofstew/seastar,kjniemi/seastar,norcimo5/seastar,hongliangzhao/seastar,kjniemi/seastar,dwdm/scylla,justintung/scylla,leejir/seastar,syuu1228/seastar,rentongzhang/scylla,eklitzke/scylla,asias/scylla,linearregression/scylla,scylladb/scylla,kjniemi/scylla,raphaelsc/seastar,mixja/seastar,eklitzke/scylla,respu/scylla,acbellini/scylla,bzero/seastar,senseb/scylla,stamhe/seastar,duarten/scylla,linearregression/seastar,ducthangho/imdb,sjperkins/seastar,avikivity/seastar,wildinto/scylla,senseb/scylla,bowlofstew/scylla,sjperkins/seastar,scylladb/scylla,slivne/seastar,gwicke/scylla,guiquanz/scylla,justintung/scylla,wildinto/scylla,bowlofstew/seastar,anzihenry/seastar,koolhazz/seastar,scylladb/scylla,phonkee/scylla