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  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]
Date:	Thu, 31 Jan 2008 09:57:40 -0600 (CST)
From:	Bruce Allen <ballen@...vity.phys.uwm.edu>
To:	David Acker <dacker@...net.com>
cc:	Bill Fink <billfink@...dspring.com>,
	SANGTAE HA <sangtae.ha@...il.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	netdev@...r.kernel.org,
	Stephen Hemminger <shemminger@...ux-foundation.org>
Subject: Re: e1000 full-duplex TCP performance well below wire speed

Hi David,

> Could this be an issue with pause frames?  At a previous job I remember 
> having issues with a similar configuration using two broadcom sb1250 3 
> gigE port devices. If I ran bidirectional tests on a single pair of 
> ports connected via cross over, it was slower than when I gave each 
> direction its own pair of ports.  The problem turned out to be that 
> pause frame generation and handling was not configured correctly.

We had PAUSE frames turned off for our testing.  The idea is to let TCP 
do the flow and congestion control.

The problem with PAUSE+TCP is that it can cause head-of-line blocking, 
where a single oversubscribed output port on a switch can PAUSE a large 
number of flows on other paths.

Cheers,
 	Bruce
--
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

Powered by blists - more mailing lists