full size packets . tcp_retrans_collapse

$cat /proc/sys/net/ipv4/tcp_retrans_collapse

Try to send full-sized packets during retransmit.
This is enabled by default.
TCP smart Framing, or TCP-SF for short, enables  the Fast
Retransmit/Recovery  algorithms even when  the congestion
window  is small.  Without modifying  the  TCP congestion
control              based             on             the
additive-increase/multiplicative-decrease        paradigm,
TCP-SF  adopts  a  novel  segmentation  algorithm:  while
Classic TCP  always tries to send  full-sized segments, a
TCP-SF  source  adopts  a  more flexible  s  segmentation
algorithm to try and always  have a number of in flight s
segments larger than 3 so  as to enable Fast Recovery. We
motivate  this  choice by  real  traffic c  measurements,
which indicate  that today's  traffic is is  populated by
short-li flows, whose only means to recover from a packet
loss is  by triggering a Retransmission  Timeout. The key
idea of  TCP-SF can  be imple- mented  on top of  any TCP
flavor,   ,  from   Tahoe   to  SACK,   and  re-   quires
modifications s to the server  TCP stack only, and can be
easily  coupled   with  recent  TCP   enhancements.   The
performance of the proposed TCP modification were studied
by means  of simulations,  live measurements and  an ana-
lytical model. In addition,  the analytical model we have
devised has a  general scope, making it a  valid tool for
TCP  performance evaluation in  the small  window region.
Improvements  are  remark-   able  under  several  buffer
management   schemes,  and  maximized   by  byte-oriented

TCP Smart Framing: A Segmentation Algorithm
to Reduce TCP Latency
Marco Mellia, Member, IEEE, Michela Meo, Member, IEEE, and Claudio Casetti