Andy Furniss wrote:
John Heffner wrote:
Andy Furniss wrote:
I've been doing some testing of my new wan connection and noticed
that when I specify a window with ip route it still changes after a
while.
Looks like this is occurring in
net/ipv4/tcp_input.c:tcp_rcv_space_adjust().
The problem really is that the window_clamp variable is overloaded.
It's used as a kind of cache for rcvbuf -> window conversion, but also
as a user-settable bound in window size. On examination, it looks
like this is also broken (in that window size won't increase) if a
user does a setsockopt(SO_RCVBUF). Can we make window_clamp a true
clamp? Then we can get rid of the hack of raising it in
tcp_rcv_space_adjust(). I can cook up a patch if interested.
-John
Thanks - I did get an answer off list (probably accidently?) to the
effect that I shouldn't rely on ip route to limit window as it's only a
hint and would make more sense if I wanted it to start really big.
I guess the other problem is that it's not well defined. :) As it
stands now though it's nearly useless if you have tcp_moderate_rcvbuf
turned on.
Playing with r_mem etc is the way to go to hard limit.
This will work, but is not available per-route or per-socket. The
purpose is really different.
-John
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