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authorFlorin Coras <fcoras@cisco.com>2017-05-24 18:03:56 -0700
committerDave Barach <openvpp@barachs.net>2017-06-09 16:47:19 +0000
commit93992a9048cb6e5dcd22de5091e72de778122627 (patch)
treef295bb870ad1614d9327828dd036fb03f60e455e /src/vnet/tcp/tcp_newreno.c
parent583dc8d3e23a780c85ebe48ea59f0338aad4df17 (diff)
Implement sack based tcp loss recovery (RFC 6675)
- refactor existing congestion control code (RFC 6582/5681). Handling of ack feedback now consists of: ack parsing, cc event detection, event handling, congestion control update - extend sack scoreboard to support sack based retransmissions - basic implementation of Eifel detection algorithm (RFC 3522) for detecting spurious retransmissions - actually initialize the per-thread frame freelist hash tables - increase worker stack size to 2mb - fix session queue node out-of-buffer handling - ensure that the local buffer cache vec_len matches reality - avoid 2x spurious event requeues when short of buffers - count out-of-buffer events - make the builtin server thread-safe - fix bihash template threading issue: need to paint -1 across uninitialized working_copy_length vector elements (via rebase from master) Change-Id: I646cb9f1add9a67d08f4a87badbcb117980ebfc4 Signed-off-by: Florin Coras <fcoras@cisco.com> Signed-off-by: Dave Barach <dbarach@cisco.com>
Diffstat (limited to 'src/vnet/tcp/tcp_newreno.c')
-rw-r--r--src/vnet/tcp/tcp_newreno.c20
1 files changed, 17 insertions, 3 deletions
diff --git a/src/vnet/tcp/tcp_newreno.c b/src/vnet/tcp/tcp_newreno.c
index 3525f4e5918..c66250e41ea 100644
--- a/src/vnet/tcp/tcp_newreno.c
+++ b/src/vnet/tcp/tcp_newreno.c
@@ -51,9 +51,23 @@ newreno_rcv_cong_ack (tcp_connection_t * tc, tcp_cc_ack_t ack_type)
}
else if (ack_type == TCP_CC_PARTIALACK)
{
- tc->cwnd -= tc->bytes_acked;
- if (tc->bytes_acked > tc->snd_mss)
- tc->bytes_acked += tc->snd_mss;
+ /* RFC 6582 Sec. 3.2 */
+ if (!tcp_opts_sack_permitted (&tc->rcv_opts))
+ {
+ /* Deflate the congestion window by the amount of new data
+ * acknowledged by the Cumulative Acknowledgment field.
+ * If the partial ACK acknowledges at least one SMSS of new data,
+ * then add back SMSS bytes to the congestion window. This
+ * artificially inflates the congestion window in order to reflect
+ * the additional segment that has left the network. This "partial
+ * window deflation" attempts to ensure that, when fast recovery
+ * eventually ends, approximately ssthresh amount of data will be
+ * outstanding in the network.*/
+ tc->cwnd = (tc->cwnd > tc->bytes_acked) ?
+ tc->cwnd - tc->bytes_acked : 0;
+ if (tc->bytes_acked > tc->snd_mss)
+ tc->cwnd += tc->snd_mss;
+ }
}
}