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author | Eric Dumazet <edumazet@google.com> | 2013-09-06 10:35:58 -0700 |
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committer | David S. Miller <davem@davemloft.net> | 2013-09-06 14:43:49 -0400 |
commit | 4e4f1fc226816905c937f9b29dabe351075dfe0f (patch) | |
tree | 6d440146005a9d075008e9cfbc5aa319dcc3767f /lib | |
parent | 0042d0c840c616186a5b09207a0e77fab7581db3 (diff) |
tcp: properly increase rcv_ssthresh for ofo packets
TCP receive window handling is multi staged.
A socket has a memory budget, static or dynamic, in sk_rcvbuf.
Because we do not really know how this memory budget translates to
a TCP window (payload), TCP announces a small initial window
(about 20 MSS).
When a packet is received, we increase TCP rcv_win depending
on the payload/truesize ratio of this packet. Good citizen
packets give a hint that it's reasonable to have rcv_win = sk_rcvbuf/2
This heuristic takes place in tcp_grow_window()
Problem is : We currently call tcp_grow_window() only for in-order
packets.
This means that reorders or packet losses stop proper grow of
rcv_win, and senders are unable to benefit from fast recovery,
or proper reordering level detection.
Really, a packet being stored in OFO queue is not a bad citizen.
It should be part of the game as in-order packets.
In our traces, we very often see sender is limited by linux small
receive windows, even if linux hosts use autotuning (DRS) and should
allow rcv_win to grow to ~3MB.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'lib')
0 files changed, 0 insertions, 0 deletions