netdev - Re: forcedeth driver hangs under heavy load

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Date:	Tue, 13 Apr 2010 13:04:58 +0100
From:	Ben Hutchings <bhutchings@...arflare.com>
To:	stephen mulcahy <smulcahy@...il.com>
Cc:	Eric Dumazet <eric.dumazet@...il.com>,
	netdev <netdev@...r.kernel.org>,
	Ben Hutchings <ben@...adent.org.uk>,
	Ayaz Abdulla <aabdulla@...dia.com>, 572201@...s.debian.org
Subject: Re: forcedeth driver hangs under heavy load

On Tue, 2010-04-13 at 12:00 +0100, stephen mulcahy wrote:
> Eric Dumazet wrote:
> > Le mardi 13 avril 2010 à 11:03 +0100, stephen mulcahy a écrit :
> >> Eric Dumazet wrote:
> >>> OK it seems forcedeth has problem with checksums ?
> >>>
> >>> Try to change "ethtool -k eth0" settings ?
> >>>
> >>> ethtool -K eth0 tso off tx off
> >> Yes, that makes an unresponsive system responsive again immediately, nice!
> >>
> >> Should the driver default to disabling this until we problem is corrected?
> >>
> >> -stephen
> > 
> > Both flags need to be disabled, or only one is OK ?
> 
> ethtool -K eth0 tx off
> 
> fixes the problem (without tso)
> 
> but running
> 
> ethtool -k eth0
> Offload parameters for eth0:
> rx-checksumming: on
> tx-checksumming: off
> scatter-gather: off
> tcp-segmentation-offload: off
> udp-fragmentation-offload: off
> generic-segmentation-offload: on
> generic-receive-offload: off
> large-receive-offload: off
> 
> seems to indicate that tso is also disabled by this - does that sound 
> correct?

That's correct - TSO requires TX offload.  What happens if you only turn
off TSO?

Ben. (wearing another hat)

-- 
Ben Hutchings, Senior Software Engineer, Solarflare Communications
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.

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