netdev - Re: Detecting TCP loss on the receiving side?

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: <48767D07.2000003@hp.com>
Date:	Thu, 10 Jul 2008 14:20:07 -0700
From:	Rick Jones <rick.jones2@...com>
To:	John Heffner <johnwheffner@...il.com>
CC:	Dan Noé <dnoe@...ebrokerage.com>,
	netdev@...r.kernel.org
Subject: Re: Detecting TCP loss on the receiving side?

John Heffner wrote:
> Looking for loss at the receiver is a bit tricky.  It doesn't look
> like struct tcp_info has enough information to do this easily.  If you
> are able to install a custom kernel on this machine, the Web100 patch
> would be able to gather enough information to figure it out.  The
> basic idea would be to look for a difference between RcvNxt and
> RcvMax.

And even then it depends on the connections having multiple segments in 
flight at one time.  Although I suppose that cuts both ways and affects 
the tracing too, but perhaps not to the same extent.

Dan - seeing "brokerage" in your email and worries about latency makes 
me think that your app(s) are pushing around lots of small messages - 
are those spread-out across lots of connections, or are they 
consolidated into a rather smaller number of connections?  Also, what is 
the magnitude of the latency in these latency events?

rick jones
--
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