netdev - Re: [PATCH 11/13] bnx2x: Forbid LRO on when XEN is enabled

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Message-Id: <20100418.205858.193699902.davem@davemloft.net>
Date:	Sun, 18 Apr 2010 20:58:58 -0700 (PDT)
From:	David Miller <davem@...emloft.net>
To:	bhutchings@...arflare.com
Cc:	vladz@...adcom.com, eilong@...adcom.com, netdev@...r.kernel.org,
	dmitry@...adcom.com
Subject: Re: [PATCH 11/13] bnx2x: Forbid LRO on when XEN is enabled

From: Ben Hutchings <bhutchings@...arflare.com>
Date: Sun, 18 Apr 2010 16:11:25 +0100

> On Sun, 2010-04-18 at 17:50 +0300, Vladislav Zolotarov wrote:
>> LRO cannot be used on virtualized environment, so it is best
>> to disable it on compile time in XEN kernel.
> [...]
> 
> If you want to cripple your performance, I'm not going to stand in your
> way, but be aware that most distribution kernels now enable CONFIG_XEN.

There is also zero reason to do this.

When the XEN code or whatever setups up the bridge, LRO will be
disabled by the bridge code.

It automatically issues ethtool LRO disable commands to the devices
involved in the bridge configuration.  And it has done this for
a _long_ time.  The ipv4 routing code will do the same.

This change is bogus and likely based upon behavior in some ancient
distribution kernel that lacks the ethtool facilities.

I absolutely refuse to apply this.
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