netdev - Re: [PATCH 00/10] Implement batching skb API

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: <20070720085737.5319d3d4@oldman>
Date:	Fri, 20 Jul 2007 08:57:37 +0100
From:	Stephen Hemminger <shemminger@...ux-foundation.org>
To:	Krishna Kumar2 <krkumar2@...ibm.com>
Cc:	davem@...emloft.net, gaagaan@...il.com,
	general@...ts.openfabrics.org, hadi@...erus.ca,
	herbert@...dor.apana.org.au, jagana@...ibm.com, jeff@...zik.org,
	johnpol@....mipt.ru, kaber@...sh.net, kumarkr@...ux.ibm.com,
	mcarlson@...adcom.com, mchan@...adcom.com, netdev@...r.kernel.org,
	peter.p.waskiewicz.jr@...el.com, rdreier@...co.com,
	rick.jones2@...com, Robert.Olsson@...a.slu.se, sri@...ibm.com,
	tgraf@...g.ch, xma@...ibm.com
Subject: Re: [PATCH 00/10] Implement batching skb API

On Fri, 20 Jul 2007 13:00:25 +0530
Krishna Kumar2 <krkumar2@...ibm.com> wrote:

> Stephen Hemminger <shemminger@...ux-foundation.org> wrote on 07/20/2007
> 12:48:48 PM:
> 
> > You may see worse performance with batching in the real world when
> > running over WAN's.  Like TSO, batching will generate back to back packet
> > trains that are subject to multi-packet synchronized loss. The problem is
> that
> > intermediate router queues are often close to full, and when a long
> string
> > of packets arrives back to back only the first ones will get in, the rest
> > get dropped.  Normal sends have at least minimal pacing so they are less
> > likely do get synchronized drop.
> 
> Hi Stephen,
> 
> OK. The difference that I could see is that in existing code, the "minimal
> pacing" also could lead to (possibly slighly lesser) loss since sends are
> quick iterations at the IP layer, while in batching sends are iterative at
> the driver layer.
> 
> Is it an issue ? Any suggestions ?

Not an immediate issue, but it is the kind of thing that could cause performance
regression reports if it was used on every interface by default.
-
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