git: TCP - Fix problems with dynamic receiver and sender buffer
commit 46e92930ee015ab6fadc97ee92142fe18d98da9e
Author: Matthew Dillon <dillon@apollo.backplane.com>
Date: Sat Aug 22 13:53:19 2009 -0700
TCP - Fix problems with dynamic receiver and sender buffer scaling
* The receive buffer dynamic scaling ran afoul of our
avoid_pure_win_update feature. Correct the calculation so this
feature properly works when the maximum receive window is smaller
the maximum sockbuf size.
* Both the send and receive buffer dynamic scaling were limited
to a maximum TCP window based on the initial window scaling negotiation,
which in turn is based on the initial size of the receive or send
sockbuf.
Negotiate a minimum window scaling of 6 (x64). This currently limits
automatic sockbuf expansion to 4MB. Further refinement is possible
as long as (1 << scaling) does not exceed 1/4 of the initial sockbuf
size.
* Reduce the maximum size of sockbuf can be dynamically scaled to from
16MB to 2MB. If someone wants more they can sysctl it up higher.
* Disable further scaling once the sockbuf size has exceeded the
originally negotiated window scale parameters. There's no gain in
doing it past that.
Summary of changes:
sys/netinet/tcp.h | 8 +++++++-
sys/netinet/tcp_input.c | 30 +++++++++++++++++++++---------
sys/netinet/tcp_output.c | 37 +++++++++++++++++++++++++++----------
sys/netinet/tcp_subr.c | 2 ++
sys/netinet/tcp_syncache.c | 5 +++--
sys/netinet/tcp_usrreq.c | 17 ++++++++++++++---
sys/netinet/tcp_var.h | 1 +
7 files changed, 75 insertions(+), 25 deletions(-)
http://gitweb.dragonflybsd.org/dragonfly.git/commitdiff/46e92930ee015ab6fadc97ee92142fe18d98da9e
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