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:	Wed, 20 Feb 2008 10:18:58 -0500
From:	Tony Battersby <tonyb@...ernetics.com>
To:	Herbert Xu <herbert@...dor.apana.org.au>
Cc:	Michael Chan <mchan@...adcom.com>,
	David Miller <davem@...emloft.net>,
	netdev <netdev@...r.kernel.org>, gregkh@...e.de,
	linux-kernel@...r.kernel.org
Subject: Re: TG3 network data corruption regression 2.6.24/2.6.23.4

Herbert Xu wrote:
> On Tue, Feb 19, 2008 at 05:14:26PM -0500, Tony Battersby wrote:
>   
>> Update: when I revert Herbert's patch in addition to applying your
>> patch, the iSCSI performance goes back up to 115 MB/s again in both
>> directions.  So it looks like turning off SG for TX didn't itself cause
>> the performance drop, but rather that the performance drop is just
>> another manifestation of whatever bug is causing the data corruption.
>>     
>
> Interesting.  So the workload that regressed is mostly RX with a
> little TX traffic? Can you try to reproduce this with something
> like netperf to eliminate other variables?
>
> This is all very puzzling since the patch in question shouldn't
> change an RX load at all.
>
> Thanks,
>   
We have established that the slowdown was caused by TCP checksum errors
and retransmits.  I assume that the slowdown in my test was due to the
light TX rather than the heavy RX.  I am no TCP protocol expert, but
perhaps heavy TX (such as iperf) might not be affected as much because
the wire stays busy while waiting for the retransmit, whereas with my
light TX iSCSI load, the wire goes idle while waiting for the retransmit
because the iSCSI state machine is stalled.

Tony

--
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