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authorYuchung Cheng <ycheng@google.com>2016-09-20 06:39:20 +0300
committerDavid S. Miller <davem@davemloft.net>2016-09-21 07:23:01 +0300
commit77bfc174c38e558a3425d3b069aa2762b2fedfdd (patch)
treea219dbdec4eac309fad1aa0761284a307ff3d762 /include/net
parent556c6b46d194cc0dbb6a5b22f1d2bbc699c86d8e (diff)
downloadlinux-77bfc174c38e558a3425d3b069aa2762b2fedfdd.tar.xz
tcp: allow congestion control to expand send buffer differently
Currently the TCP send buffer expands to twice cwnd, in order to allow limited transmits in the CA_Recovery state. This assumes that cwnd does not increase in the CA_Recovery. For some congestion control algorithms, like the upcoming BBR module, if the losses in recovery do not indicate congestion then we may continue to raise cwnd multiplicatively in recovery. In such cases the current multiplier will falsely limit the sending rate, much as if it were limited by the application. This commit adds an optional congestion control callback to use a different multiplier to expand the TCP send buffer. For congestion control modules that do not specificy this callback, TCP continues to use the previous default of 2. Signed-off-by: Van Jacobson <vanj@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Nandita Dukkipati <nanditad@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com> Acked-by: Stephen Hemminger <stephen@networkplumber.org> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/net')
-rw-r--r--include/net/tcp.h2
1 files changed, 2 insertions, 0 deletions
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 349204130d84..1aa9628ae608 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -917,6 +917,8 @@ struct tcp_congestion_ops {
void (*pkts_acked)(struct sock *sk, const struct ack_sample *sample);
/* suggest number of segments for each skb to transmit (optional) */
u32 (*tso_segs_goal)(struct sock *sk);
+ /* returns the multiplier used in tcp_sndbuf_expand (optional) */
+ u32 (*sndbuf_expand)(struct sock *sk);
/* get info for inet_diag (optional) */
size_t (*get_info)(struct sock *sk, u32 ext, int *attr,
union tcp_cc_info *info);