netdev - Re: [PATCH 4/5] dccp: Deprecate Ack Ratio sysctl

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: <20081116.225636.32402768.davem@davemloft.net>
Date:	Sun, 16 Nov 2008 22:56:36 -0800 (PST)
From:	David Miller <davem@...emloft.net>
To:	gerrit@....abdn.ac.uk
Cc:	dccp@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCH 4/5] dccp: Deprecate Ack Ratio sysctl

From: Gerrit Renker <gerrit@....abdn.ac.uk>
Date: Sat, 15 Nov 2008 13:11:18 +0100

> This patch deprecates the Ack Ratio sysctl, since
>  * Ack Ratio is entirely ignored by CCID-3 and CCID-4,
>  * Ack Ratio currently doesn't work in CCID-2 (i.e. is always set to 1);
>  * even if it would work in CCID-2, there is no point for a user to change it:
>    - Ack Ratio is constrained by cwnd (RFC 4341, 6.1.2),
>    - if Ack Ratio > cwnd, the system resorts to spurious RTO timeouts
>      (since waiting for Acks which will never arrive in this window),
>    - cwnd is not a user-configurable value.
> 
> The only reasonable place for Ack Ratio is to print it for debugging. It is
> planned to do this later on, as part of e.g. dccp_probe.
> 
> With this patch Ack Ratio is now under full control of feature negotiation:
>  * Ack Ratio is resolved as a dependency of the selected CCID;
>  * if the chosen CCID supports it (i.e. CCID == CCID-2), Ack Ratio is set to
>    the default of 2, following RFC 4340, 11.3 - "New connections start with Ack
>    Ratio 2 for both endpoints";
>  * what happens then is part of another patch set, since it concerns the
>    dynamic update of Ack Ratio while the connection is in full flight.
> 
> Thanks to Tomasz Grobelny for discussion leading up to this patch.
> 
> Signed-off-by: Gerrit Renker <gerrit@....abdn.ac.uk>
> Acked-by: Arnaldo Carvalho de Melo <acme@...hat.com>

Applied.
--
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