From: "H.K. Jerry Chu" <hkjerry.chu@gmail.com>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Alexander Bergmann <alex@linlab.net>,
David Miller <davem@davemloft.net>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/1] tcp: Wrong timeout for SYN segments
Date: Thu, 30 Aug 2012 10:59:39 -0700 [thread overview]
Message-ID: <CAFbMe2OtGmon9iWdC89T3RkWp526XCbNo-3SFAZ+nBmQRgT0Vg@mail.gmail.com> (raw)
In-Reply-To: <1346332350.2586.10.camel@edumazet-glaptop>
On Thu, Aug 30, 2012 at 6:12 AM, Eric Dumazet <eric.dumazet@gmail.com> wrote:
> On Wed, 2012-08-29 at 10:25 -0700, H.K. Jerry Chu wrote:
>
>> But it probably matter slightly more for TCP Fast Open (the server
>> side patch has
>> been completed and will be posted soon, after I finish breaking it up
>> into smaller
>> pieces for ease of review purpose), when a full socket will be created with data
>> passed to the app upon a valid SYN+data. Dropping a fully functioning socket
>> won't be the same as dropping a request_sock unknown to the app and letting
>> the other side retransmitting SYN (w/o data this time).
>>
>> >
>> > Sure, RFC numbers are what they are, but in practice, I doubt someone
>> > will really miss the extra SYNACK sent after ~32 seconds, since it would
>> > matter only for the last SYN attempted.
>>
>> I'd slightly prefer 1 extra retry plus longer wait time just to make
>> TCP Fast Open
>> a little more robust (even though the app protocol is required to be
>> idempotent).
>> But this is not a showstopper.
>
> Thats very good points indeed, thanks.
>
> Maybe we can increase SYNACK max retrans only if the FastOpen SYN cookie
> was validated.
>
> This way, we increase reliability without amplifying the effect of wild
> SYN packets.
Ok, will use sysctl_tcp_synack_retries + 1 in tcp_fastopen_synack_timer() of my
upcoming TCP Fast Open server patch (hope to submit today).
Jerry
>
>
>
prev parent reply other threads:[~2012-08-30 17:59 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-21 23:29 [PATCH 1/1] tcp: Wrong timeout for SYN segments Alex Bergmann
2012-08-22 8:06 ` Eric Dumazet
2012-08-22 8:48 ` Alex Bergmann
2012-08-22 8:58 ` Eric Dumazet
2012-08-22 9:29 ` Alex Bergmann
2012-08-22 9:59 ` Eric Dumazet
2012-08-22 10:03 ` Eric Dumazet
2012-08-22 17:29 ` H.K. Jerry Chu
2012-08-22 16:44 ` H.K. Jerry Chu
[not found] ` <CAFbMe2M7ekc94bQk7vTS1LhScPd49VZ-zKOCUXhqwxXtL-nkuA@mail.gmail.com>
2012-08-23 11:58 ` Alex Bergmann
2012-08-23 12:15 ` Eric Dumazet
2012-08-23 12:35 ` David Laight
2012-08-23 12:51 ` Eric Dumazet
2012-08-23 12:37 ` Alex Bergmann
2012-08-23 12:49 ` Eric Dumazet
2012-08-24 12:17 ` Alex Bergmann
2012-08-24 17:42 ` David Miller
2012-08-25 8:48 ` Alexander Bergmann
2012-08-25 9:01 ` Eric Dumazet
2012-08-28 8:44 ` Carsten Wolff
[not found] ` <1346414260.2591.8.camel@edumazet-glaptop>
2012-08-31 12:48 ` Alexander Bergmann
2012-08-31 13:25 ` Eric Dumazet
2012-08-31 19:42 ` David Miller
2012-08-31 19:47 ` David Miller
2012-08-29 4:34 ` H.K. Jerry Chu
2012-08-29 8:51 ` Eric Dumazet
2012-08-29 17:25 ` H.K. Jerry Chu
2012-08-30 13:12 ` Eric Dumazet
2012-08-30 16:45 ` David Miller
2012-08-30 18:04 ` H.K. Jerry Chu
2012-08-30 17:59 ` H.K. Jerry Chu [this message]
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