From: David Miller <davem@davemloft.net>
To: ycheng@google.com
Cc: netdev@vger.kernel.org, ncardwell@google.com,
edumazet@google.com, soheil@google.com
Subject: Re: [PATCH net] tcp: restrict F-RTO to work-around broken middle-boxes
Date: Fri, 07 Apr 2017 11:45:11 -0700 (PDT) [thread overview]
Message-ID: <20170407.114511.2181178908974978179.davem@davemloft.net> (raw)
In-Reply-To: <20170407184205.168217-1-ycheng@google.com>
From: Yuchung Cheng <ycheng@google.com>
Date: Fri, 7 Apr 2017 11:42:05 -0700
> The recent extension of F-RTO 89fe18e44 ("tcp: extend F-RTO
> to catch more spurious timeouts") interacts badly with certain
> broken middle-boxes. These broken boxes modify and falsely raise
> the receive window on the ACKs. During a timeout induced recovery,
> F-RTO would send new data packets to probe if the timeout is false
> or not. Since the receive window is falsely raised, the receiver
> would silently drop these F-RTO packets. The recovery would take N
> (exponentially backoff) timeouts to repair N packet losses. A TCP
> performance killer.
>
> Due to this unfortunate situation, this patch removes this extension
> to revert F-RTO back to the RFC specification.
>
> Fixes: 89fe18e44f7e ("tcp: extend F-RTO to catch more spurious timeouts")
> Signed-off-by: Yuchung Cheng <ycheng@google.com>
> Signed-off-by: Neal Cardwell <ncardwell@google.com>
> Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
> Signed-off-by: Eric Dumazet <edumazet@google.com>
Applied, thank you.
next prev parent reply other threads:[~2017-04-07 18:45 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-07 18:42 [PATCH net] tcp: restrict F-RTO to work-around broken middle-boxes Yuchung Cheng
2017-04-07 18:45 ` David Miller [this message]
2018-02-18 21:02 ` Teodor Milkov
2018-02-19 13:38 ` Neal Cardwell
2018-02-19 16:17 ` Teodor Milkov
2018-02-19 18:05 ` Neal Cardwell
2018-02-21 12:38 ` Teodor Milkov
2018-02-21 16:57 ` Neal Cardwell
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