netdev - Re: TCP rx window autotuning harmful at LAN context

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <1e41a3230903100823h5d5768d9wb9f36eb294840814@mail.gmail.com>
Date:	Tue, 10 Mar 2009 08:23:34 -0700
From:	John Heffner <johnwheffner@...il.com>
To:	Marian Ďurkovič <md@....sk>
Cc:	David Miller <davem@...emloft.net>, netdev@...r.kernel.org
Subject: Re: TCP rx window autotuning harmful at LAN context

On Tue, Mar 10, 2009 at 4:46 AM, Marian Ďurkovič <md@....sk> wrote:
> On Tue, Mar 10, 2009 at 04:30:19AM -0700, David Miller wrote:
>> From: Marian Ďurkovič <md@....sk>
>> Date: Tue, 10 Mar 2009 11:49:56 +0100
>>
>> > Sender does not have the relevant info to implement this - it might be
>> > connected by 10 GE to the highspeed backbone.
>>
>> Yes, the sender does indeed have this information, and using it is
>> exactly what congestion control algorithms such as VEGAS try to do.
>>
>> They look at both round trip times and bandwith as they increase the
>> send congestion window.  And if round trips increase without a
>> corresponding increase in bandwidth, they stop increasing.
>
> Yes, but that's actual bandwidth between sender and receiver, not
> the hard BW limit of the receiver's NIC. My intention is just to introduce
> some safety belt preventing autotuning to increase the rx window
> into MB ranges when RTT is very low.

Nowhere in our proposal do you use NIC bandwidth.  What you proposed
can be done easily at the sender.

  -John
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html