netdev - Re: [patch next 4/4] netxen: disable rss for GbE ports

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Message-Id: <20090506.163142.112368323.davem@davemloft.net>
Date:	Wed, 06 May 2009 16:31:42 -0700 (PDT)
From:	David Miller <davem@...emloft.net>
To:	dhananjay@...xen.com
Cc:	netdev@...r.kernel.org
Subject: Re: [patch next 4/4] netxen: disable rss for GbE ports

From: Dhananjay Phadke <dhananjay@...xen.com>
Date: Wed, 6 May 2009 16:06:30 -0700

> The reason for RSS was to distribute the ingress traffic
> to different CPUs. At 10Gbps, without RSS, one CPU was
> saturating, acting as bottleneck. I can do 1Gbps with
> only one CPU only 50% saturated, this to on a low end
> server.
> 
> The fallout is more msix vectors being consumed for RSS,
> when they don't really bring any performance gain.
> 
> Since NetXen has single driver, unlike others, it needs
> to be dealt based on NIC board type.

Thanks for ignoring my email.

I'll say it again, maybe you'll listen this time.

If a user has very cpu intensive netfilter or routing
rules installed, the RSS flow seperation to different
CPUs can help even at 1GB speeds.

Therefore, your change will introduce performance regressions.
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