tcp: sndbuf autotuning improvements
tcp_fixup_sndbuf() is underestimating initial send buffer requirements.
It was not noticed because big GSO packets were escaping the limitation,
but with smaller TSO packets (or TSO/GSO/SG off), application hits
sk_sndbuf before having a chance to fill enough packets in socket write
queue.
- initial cwnd can be bigger than 10 for specific routes
- SKB_TRUESIZE() is a bit under real needs in some cases,
because of power-of-two rounding in kmalloc()
- Fast Recovery (RFC 5681 3.2) : Cubic needs 70% factor
- Extra cushion (application might react slowly to POLLOUT)
tcp_v4_conn_req_fastopen() needs to call tcp_init_metrics() before
calling tcp_init_buffer_space()
Then we realize tcp_new_space() should call tcp_fixup_sndbuf()
instead of duplicating this stuff.
Rename tcp_fixup_sndbuf() to tcp_sndbuf_expand() to be more
descriptive.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Acked-by: Maciej Żenczykowski <maze@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index b14266b..5d6b1a6 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1410,8 +1410,8 @@
inet_csk(child)->icsk_af_ops->rebuild_header(child);
tcp_init_congestion_control(child);
tcp_mtup_init(child);
- tcp_init_buffer_space(child);
tcp_init_metrics(child);
+ tcp_init_buffer_space(child);
/* Queue the data carried in the SYN packet. We need to first
* bump skb's refcnt because the caller will attempt to free it.