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From: tsuna <tsunanet@gmail.com>
To: Alexander Zimmermann <alexander.zimmermann@comsys.rwth-aachen.de>
Cc: David Miller <davem@davemloft.net>,
	kuznet@ms2.inr.ac.ru, pekkas@netcore.fi, jmorris@namei.org,
	yoshfuji@linux-ipv6.org, kaber@trash.net, hagen@jauu.net,
	eric.dumazet@gmail.com, netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] tcp: Implement a two-level initial RTO as per draft RFC 2988bis-02.
Date: Wed, 18 May 2011 23:42:30 -0700	[thread overview]
Message-ID: <BANLkTiku9KTHCm59cib5KY8mz0ewSLsHFQ@mail.gmail.com> (raw)
In-Reply-To: <C70B920C-6176-481B-B6D2-E52769291EBC@comsys.rwth-aachen.de>

On Wed, May 18, 2011 at 11:36 PM, Alexander Zimmermann
<alexander.zimmermann@comsys.rwth-aachen.de> wrote:
> If you set the initRTO=0.1s, it's good for me but bad for the rest of the
> world. That's the difference.
>
> Or do you want to implement a lower barrier of 1sec so that you can ensure
> that nobody set the initRTO lower than 1s?

Oh, I see.  Yes, there is a lower bound (and an upper bound) on what
values the kernel will accept as initRTO.  In the patch "Implement a
two-level initial RTO as per draft RFC 2988bis-02" above, I re-used
TCP_RTO_MIN and TCP_RTO_MAX in net/ipv4/sysctl_net_ipv4.c in order to
prevent users from setting a minRTO that's outside this range.  They
are defined as follows in tcp.h:

#define TCP_RTO_MAX     ((unsigned)(120*HZ))
#define TCP_RTO_MIN     ((unsigned)(HZ/5))

So we're talking about a [200ms ; 120s] range no matter what.

-- 
Benoit "tsuna" Sigoure
Software Engineer @ www.StumbleUpon.com

  reply	other threads:[~2011-05-19  6:42 UTC|newest]

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-05-17  7:40 [PATCH] tcp: Expose the initial RTO via a new sysctl Benoit Sigoure
2011-05-17  7:40 ` Benoit Sigoure
2011-05-17  8:01   ` Alexander Zimmermann
2011-05-17  8:34     ` Eric Dumazet
2011-05-17  8:07   ` Eric Dumazet
2011-05-17 11:02     ` Hagen Paul Pfeifer
2011-05-17 12:20       ` Eric Dumazet
2011-05-18 10:43     ` Benoit Sigoure
2011-05-18 19:26       ` David Miller
2011-05-18 19:40         ` tsuna
2011-05-18 19:52           ` David Miller
2011-05-18 20:20             ` Hagen Paul Pfeifer
2011-05-18 20:23               ` David Miller
2011-05-18 20:27                 ` Hagen Paul Pfeifer
2011-05-20 10:27               ` H.K. Jerry Chu
2011-05-20 11:00                 ` Hagen Paul Pfeifer
2011-05-20 12:37                   ` Alan Cox
2011-05-21  0:06                   ` H.K. Jerry Chu
2011-05-31 14:48                     ` tsuna
2011-05-31 15:25                       ` Hagen Paul Pfeifer
2011-05-31 15:28                         ` tsuna
2011-05-31 15:43                           ` Hagen Paul Pfeifer
2011-05-19  2:22             ` [PATCH] tcp: Implement a two-level initial RTO as per draft RFC 2988bis-02 Benoit Sigoure
2011-05-19  2:36               ` David Miller
2011-05-19  3:56                 ` tsuna
2011-05-19  4:14                   ` David Miller
2011-05-19  4:33                     ` tsuna
2011-05-19  5:46                       ` David Miller
2011-05-19  6:36                         ` [PATCH] tcp: Lower the initial RTO to 1s " Benoit Sigoure
2011-05-19 17:42                           ` Yuchung Cheng
2011-05-19  6:47                         ` Benoit Sigoure
2011-05-19 20:16                           ` David Miller
2011-05-19  6:10                       ` [PATCH] tcp: Implement a two-level initial RTO " Alexander Zimmermann
2011-05-19  6:25                         ` tsuna
2011-05-19  6:36                           ` Alexander Zimmermann
2011-05-19  6:42                             ` tsuna [this message]
2011-05-19  6:52                               ` Alexander Zimmermann
2011-05-19  7:07                                 ` tsuna
2011-05-19  8:02                                 ` Hagen Paul Pfeifer
2011-05-19 16:40                                   ` tsuna
2011-05-19 16:55                                     ` Alexander Zimmermann
2011-05-19 17:11                                       ` tsuna
2011-05-19 19:27                                         ` David Miller
2011-05-19 20:30                                           ` tsuna
2011-05-20  2:01           ` [PATCH] tcp: Expose the initial RTO via a new sysctl H.K. Jerry Chu

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