netdev - Re: [PATCH v3 3/3] tcp: early retransmit: delayed fast retransmit

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: <CADVnQyn6K8xH=wwi7pN0wsKS4wEhksi2pB0KbTaSDqLGWmnBaw@mail.gmail.com>
Date:	Wed, 2 May 2012 15:34:41 -0400
From:	Neal Cardwell <ncardwell@...gle.com>
To:	Yuchung Cheng <ycheng@...gle.com>
Cc:	davem@...emloft.net, ilpo.jarvinen@...sinki.fi,
	nanditad@...gle.com, netdev@...r.kernel.org
Subject: Re: [PATCH v3 3/3] tcp: early retransmit: delayed fast retransmit

On Wed, May 2, 2012 at 2:46 PM, Yuchung Cheng <ycheng@...gle.com> wrote:
> Implementing the advanced early retransmit (sysctl_tcp_early_retrans==2).
> Delays the fast retransmit by an interval of RTT/4. We borrow the
> RTO timer to implement the delay. If we receive another ACK or send
> a new packet, the timer is cancelled and restored to original RTO
> value offset by time elapsed.  When the delayed-ER timer fires,
> we enter fast recovery and perform fast retransmit.
>
> Signed-off-by: Yuchung Cheng <ycheng@...gle.com>
> ---
> ChangeLog in v2:
>  - Set sysctl_tcp_early_retrans default to 2
> ChangeLog in v3:
>  - use separate u8 for early retrans stats in tcp_sock
>  - disable ER if detects any reordering

After reading patch 3 of the series, I see that patch 3 incorporates
most of those suggestions from Monday. I think it would be quite a bit
cleaner to just have patch 2 of the series put the
tcp_disable_early_retrans() call and tcp_sock fields in the ultimately
desired place, rather than having patch 2 put them somewhere and patch
3 move them, but maybe that's just me.

When all the patches in the series are applied, the one issue I still
see is that frto_counter is in a new place, a bit further away from
frto_highmark than it used to be before the patch series. I think it
would be good  to keep frto_counter in its original location, back up
nearer to frto_highmark.

neal
--
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