netdev - Re: [PATCH net v2] gso: Update tunnel segmentation to support Tx checksum offload

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Date:	Thu, 11 Jul 2013 00:45:19 -0700
From:	Pravin Shelar <pshelar@...ira.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	Alexander Duyck <alexander.h.duyck@...el.com>,
	netdev@...r.kernel.org, stephen@...workplumber.org,
	joseph.gasparakis@...el.com, jesse@...ira.com
Subject: Re: [PATCH net v2] gso: Update tunnel segmentation to support Tx
 checksum offload

On Wed, Jul 10, 2013 at 5:42 PM, Eric Dumazet <eric.dumazet@...il.com> wrote:
> On Wed, 2013-07-10 at 17:05 -0700, Alexander Duyck wrote:
>> This change makes it so that the GRE and VXLAN tunnels can make use of Tx
>> checksum offload support provided by some drivers via the hw_enc_features.
>> Without this fix enabling GSO means sacrificing Tx checksum offload and
>> this actually leads to a performance regression as shown below:
>>
>>             Utilization
>>             Send
>> Throughput  local         GSO
>> 10^6bits/s  % S           state
>>   6276.51   8.39          enabled
>>   7123.52   8.42          disabled
>
> While testing your patch, I discovered TSO support is completely broken
> on GRE, using bnx2x testbed.
>
> Oh well.
>
> It seems Nicira guys do not test a lot their patches.
>
>
Nice speculation ;)

I did some digging and found following commit causing problem with GRE
TSO on bnx setup.

c957d09ffda417f6c8e3d1f10e2b05228607d6d7 is the first bad commit
commit c957d09ffda417f6c8e3d1f10e2b05228607d6d7
Author: Yuval Mintz <yuvalmin@...adcom.com>
Date:   Tue Jun 25 08:50:11 2013 +0300

    bnx2x: Remove sparse and coccinelle warnings

    This patch solves several sparse issues as well as an unneeded semicolon
    found via coccinelle.

    Signed-off-by: Yuval Mintz <yuvalmin@...adcom.com>
    Signed-off-by: Dmitry Kravkov <dmitry@...adcom.com>
    Signed-off-by: Ariel Elior <ariele@...adcom.com>
    Signed-off-by: Eilon Greenstein <eilong@...adcom.com>
    Signed-off-by: David S. Miller <davem@...emloft.net>
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