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authorFlorin Coras <fcoras@cisco.com>2020-07-29 23:03:39 -0700
committerDave Barach <openvpp@barachs.net>2020-08-20 16:58:33 +0000
commitcc4d6d022fb0d4b4f0ea9f63e9c6b1c0e8d95cca (patch)
tree502798f83b8cbfe1cd3c697960d2633c79d9bbfa /src/vnet/tcp/tcp_sack.c
parentad1e455f4d27624f79ca441114932e274cda8ab1 (diff)
tcp: track reorder with sacks
Type: feature Change-Id: I041bff2e8d589c171661de286fa1503531dff891 Signed-off-by: Florin Coras <fcoras@cisco.com>
Diffstat (limited to 'src/vnet/tcp/tcp_sack.c')
-rw-r--r--src/vnet/tcp/tcp_sack.c62
1 files changed, 43 insertions, 19 deletions
diff --git a/src/vnet/tcp/tcp_sack.c b/src/vnet/tcp/tcp_sack.c
index b9e1166d779..8f51b517361 100644
--- a/src/vnet/tcp/tcp_sack.c
+++ b/src/vnet/tcp/tcp_sack.c
@@ -88,10 +88,23 @@ scoreboard_insert_hole (sack_scoreboard_t * sb, u32 prev_index,
}
always_inline void
-scoreboard_update_sacked_rxt (sack_scoreboard_t * sb, u32 start, u32 end,
- u8 has_rxt)
+scoreboard_update_sacked (sack_scoreboard_t * sb, u32 start, u32 end,
+ u8 has_rxt, u16 snd_mss)
{
- if (!has_rxt || seq_geq (start, sb->high_rxt))
+ if (!has_rxt)
+ {
+ /* Sequence was not retransmitted but it was sacked. Estimate reorder
+ * only if not in congestion recovery */
+ if (seq_lt (start, sb->high_sacked))
+ {
+ u32 reord = (sb->high_sacked - start + snd_mss - 1) / snd_mss;
+ reord = clib_min (reord, TCP_MAX_SACK_REORDER);
+ sb->reorder = clib_max (sb->reorder, reord);
+ }
+ return;
+ }
+
+ if (seq_geq (start, sb->high_rxt))
return;
sb->rxt_sacked +=
@@ -125,8 +138,14 @@ scoreboard_update_bytes (sack_scoreboard_t * sb, u32 ack, u32 snd_mss)
blks = 1;
}
- while (sacked < (TCP_DUPACK_THRESHOLD - 1) * snd_mss
- && blks < TCP_DUPACK_THRESHOLD)
+ /* As per RFC 6675 a sequence number is lost if:
+ * DupThresh discontiguous SACKed sequences have arrived above
+ * 'SeqNum' or more than (DupThresh - 1) * SMSS bytes with sequence
+ * numbers greater than 'SeqNum' have been SACKed.
+ * To avoid spurious retransmits, use reordering estimate instead of
+ * DupThresh to detect loss.
+ */
+ while (sacked <= (sb->reorder - 1) * snd_mss && blks < sb->reorder)
{
if (right->is_lost)
sb->lost_bytes += scoreboard_hole_bytes (right);
@@ -251,6 +270,7 @@ scoreboard_init (sack_scoreboard_t * sb)
sb->head = TCP_INVALID_SACK_HOLE_INDEX;
sb->tail = TCP_INVALID_SACK_HOLE_INDEX;
sb->cur_rxt_hole = TCP_INVALID_SACK_HOLE_INDEX;
+ sb->reorder = TCP_DUPACK_THRESHOLD;
}
void
@@ -270,6 +290,7 @@ scoreboard_clear (sack_scoreboard_t * sb)
sb->last_lost_bytes = 0;
sb->cur_rxt_hole = TCP_INVALID_SACK_HOLE_INDEX;
sb->is_reneging = 0;
+ sb->reorder = TCP_DUPACK_THRESHOLD;
}
void
@@ -307,7 +328,7 @@ tcp_rcv_sacks (tcp_connection_t * tc, u32 ack)
sack_scoreboard_hole_t *hole, *next_hole;
sack_scoreboard_t *sb = &tc->sack_sb;
sack_block_t *blk, *rcv_sacks;
- u32 blk_index = 0, i, j;
+ u32 blk_index = 0, i, j, high_sacked;
u8 has_rxt;
sb->last_sacked_bytes = 0;
@@ -391,8 +412,9 @@ tcp_rcv_sacks (tcp_connection_t * tc, u32 ack)
hole = scoreboard_insert_hole (sb, TCP_INVALID_SACK_HOLE_INDEX,
tc->snd_una, tc->snd_nxt);
sb->tail = scoreboard_hole_index (sb, hole);
+ sb->high_sacked = tc->snd_una;
}
- sb->high_sacked = rcv_sacks[vec_len (rcv_sacks) - 1].end;
+ high_sacked = rcv_sacks[vec_len (rcv_sacks) - 1].end;
}
else
{
@@ -412,11 +434,10 @@ tcp_rcv_sacks (tcp_connection_t * tc, u32 ack)
tc->snd_nxt);
}
}
-
/* Keep track of max byte sacked for when the last hole
* is acked */
- sb->high_sacked = seq_max (rcv_sacks[vec_len (rcv_sacks) - 1].end,
- sb->high_sacked);
+ high_sacked = seq_max (rcv_sacks[vec_len (rcv_sacks) - 1].end,
+ sb->high_sacked);
}
/* Walk the holes with the SACK blocks */
@@ -442,7 +463,8 @@ tcp_rcv_sacks (tcp_connection_t * tc, u32 ack)
/* If covered by ack, compute delivered bytes */
if (blk->end == ack)
{
- u32 sacked = next_hole ? next_hole->start : sb->high_sacked;
+ u32 sacked = next_hole ? next_hole->start :
+ seq_max (sb->high_sacked, hole->end);
if (PREDICT_FALSE (seq_lt (ack, sacked)))
{
sb->last_bytes_delivered += ack - hole->end;
@@ -454,8 +476,8 @@ tcp_rcv_sacks (tcp_connection_t * tc, u32 ack)
sb->is_reneging = 0;
}
}
- scoreboard_update_sacked_rxt (sb, hole->start, hole->end,
- has_rxt);
+ scoreboard_update_sacked (sb, hole->start, hole->end,
+ has_rxt, tc->snd_mss);
scoreboard_remove_hole (sb, hole);
hole = next_hole;
}
@@ -464,8 +486,8 @@ tcp_rcv_sacks (tcp_connection_t * tc, u32 ack)
{
if (seq_gt (blk->end, hole->start))
{
- scoreboard_update_sacked_rxt (sb, hole->start, blk->end,
- has_rxt);
+ scoreboard_update_sacked (sb, hole->start, blk->end,
+ has_rxt, tc->snd_mss);
hole->start = blk->end;
}
blk_index++;
@@ -482,23 +504,25 @@ tcp_rcv_sacks (tcp_connection_t * tc, u32 ack)
/* Pool might've moved */
hole = scoreboard_get_hole (sb, hole_index);
hole->end = blk->start;
+ next_hole->is_lost = hole->is_lost;
- scoreboard_update_sacked_rxt (sb, blk->start, blk->end,
- has_rxt);
+ scoreboard_update_sacked (sb, blk->start, blk->end,
+ has_rxt, tc->snd_mss);
blk_index++;
ASSERT (hole->next == scoreboard_hole_index (sb, next_hole));
}
else if (seq_lt (blk->start, hole->end))
{
- scoreboard_update_sacked_rxt (sb, blk->start, hole->end,
- has_rxt);
+ scoreboard_update_sacked (sb, blk->start, hole->end,
+ has_rxt, tc->snd_mss);
hole->end = blk->start;
}
hole = scoreboard_next_hole (sb, hole);
}
}
+ sb->high_sacked = high_sacked;
scoreboard_update_bytes (sb, ack, tc->snd_mss);
ASSERT (sb->last_sacked_bytes <= sb->sacked_bytes || tcp_in_recovery (tc));