tcp: send enough dupacks to cover all sack holes
Make sure we send enough dupacks to cover all the holes created in the
last frame received. Also make sure we send all the blocks, not just the
first.
Change-Id: I9597a34ac14473d1cc3ad07d65bc37043e3d0582
Signed-off-by: Florin Coras <fcoras@cisco.com>
diff --git a/src/vnet/tcp/tcp_output.c b/src/vnet/tcp/tcp_output.c
index 725ffec..4de479c 100644
--- a/src/vnet/tcp/tcp_output.c
+++ b/src/vnet/tcp/tcp_output.c
@@ -253,14 +253,12 @@
if (tcp_opts_sack (opts))
{
int i;
- u32 n_sack_blocks = clib_min (vec_len (opts->sacks),
- TCP_OPTS_MAX_SACK_BLOCKS);
- if (n_sack_blocks != 0)
+ if (opts->n_sack_blocks != 0)
{
*data++ = TCP_OPTION_SACK_BLOCK;
- *data++ = 2 + n_sack_blocks * TCP_OPTION_LEN_SACK_BLOCK;
- for (i = 0; i < n_sack_blocks; i++)
+ *data++ = 2 + opts->n_sack_blocks * TCP_OPTION_LEN_SACK_BLOCK;
+ for (i = 0; i < opts->n_sack_blocks; i++)
{
buf = clib_host_to_net_u32 (opts->sacks[i].start);
clib_memcpy_fast (data, &buf, seq_len);
@@ -269,7 +267,7 @@
clib_memcpy_fast (data, &buf, seq_len);
data += seq_len;
}
- opts_len += 2 + n_sack_blocks * TCP_OPTION_LEN_SACK_BLOCK;
+ opts_len += 2 + opts->n_sack_blocks * TCP_OPTION_LEN_SACK_BLOCK;
}
}
@@ -372,9 +370,13 @@
if (vec_len (tc->snd_sacks))
{
opts->flags |= TCP_OPTS_FLAG_SACK;
- opts->sacks = tc->snd_sacks;
- opts->n_sack_blocks = clib_min (vec_len (tc->snd_sacks),
+ if (tc->snd_sack_pos >= vec_len (tc->snd_sacks))
+ tc->snd_sack_pos = 0;
+ opts->sacks = &tc->snd_sacks[tc->snd_sack_pos];
+ opts->n_sack_blocks = vec_len (tc->snd_sacks) - tc->snd_sack_pos;
+ opts->n_sack_blocks = clib_min (opts->n_sack_blocks,
TCP_OPTS_MAX_SACK_BLOCKS);
+ tc->snd_sack_pos += opts->n_sack_blocks;
len += 2 + TCP_OPTION_LEN_SACK_BLOCK * opts->n_sack_blocks;
}
}
@@ -1250,14 +1252,34 @@
{
tc = tcp_connection_get (pending_acks[i], thread_index);
tc->flags &= ~TCP_CONN_SNDACK;
- n_acks = clib_max (1, tc->pending_dupacks);
+ if (!tc->pending_dupacks)
+ {
+ tcp_send_ack (tc);
+ continue;
+ }
+
/* If we're supposed to send dupacks but have no ooo data
* send only one ack */
- if (tc->pending_dupacks && !vec_len (tc->snd_sacks))
- n_acks = 1;
+ if (!vec_len (tc->snd_sacks))
+ {
+ tcp_send_ack (tc);
+ continue;
+ }
+
+ /* Start with first sack block */
+ tc->snd_sack_pos = 0;
+
+ /* Generate enough dupacks to cover all sack blocks. Do not generate
+ * more sacks than the number of packets received. But do generate at
+ * least 3, i.e., the number needed to signal congestion, if needed. */
+ n_acks = vec_len (tc->snd_sacks) / TCP_OPTS_MAX_SACK_BLOCKS;
+ n_acks = clib_min (n_acks, tc->pending_dupacks);
+ n_acks = clib_max (n_acks, clib_min (tc->pending_dupacks, 3));
for (j = 0; j < n_acks; j++)
tcp_send_ack (tc);
+
tc->pending_dupacks = 0;
+ tc->snd_sack_pos = 0;
}
_vec_len (wrk->pending_acks) = 0;
}