diff options
author | Jason Xing <kernelxing@tencent.com> | 2023-08-11 10:37:47 +0800 |
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committer | David S. Miller <davem@davemloft.net> | 2023-08-15 20:24:04 +0100 |
commit | e4dd0d3a2f64b8bd8029ec70f52bdbebd0644408 (patch) | |
tree | 6cf24c26f399fdb42cb17c48d46b76bda20ec507 /net/netfilter | |
parent | 8a519a572598b7c0c07b02f69bf5b4e8dd4b2d7d (diff) |
net: fix the RTO timer retransmitting skb every 1ms if linear option is enabled
In the real workload, I encountered an issue which could cause the RTO
timer to retransmit the skb per 1ms with linear option enabled. The amount
of lost-retransmitted skbs can go up to 1000+ instantly.
The root cause is that if the icsk_rto happens to be zero in the 6th round
(which is the TCP_THIN_LINEAR_RETRIES value), then it will always be zero
due to the changed calculation method in tcp_retransmit_timer() as follows:
icsk->icsk_rto = min(icsk->icsk_rto << 1, TCP_RTO_MAX);
Above line could be converted to
icsk->icsk_rto = min(0 << 1, TCP_RTO_MAX) = 0
Therefore, the timer expires so quickly without any doubt.
I read through the RFC 6298 and found that the RTO value can be rounded
up to a certain value, in Linux, say TCP_RTO_MIN as default, which is
regarded as the lower bound in this patch as suggested by Eric.
Fixes: 36e31b0af587 ("net: TCP thin linear timeouts")
Suggested-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jason Xing <kernelxing@tencent.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/netfilter')
0 files changed, 0 insertions, 0 deletions