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Date: Wed, 4 Feb 2015 13:53:11 +0100
Message-ID: <CA+BoTQ=qmCZz4CmSOvCOzMLowrDEG12XBffkTcYxjGqVD9604g@mail.gmail.com> (sfid-20150204_135320_650134_35405608)
Subject: Re: Throughput regression with `tcp: refine TSO autosizing`
From: Michal Kazior <michal.kazior@tieto.com>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: linux-wireless <linux-wireless@vger.kernel.org>,
	Network Development <netdev@vger.kernel.org>,
	eyalpe@dev.mellanox.co.il
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List-ID: <linux-wireless.vger.kernel.org>

On 4 February 2015 at 13:38, Eric Dumazet <eric.dumazet@gmail.com> wrote:
> On Wed, 2015-02-04 at 13:22 +0100, Michal Kazior wrote:
>> On 4 February 2015 at 12:57, Eric Dumazet <eric.dumazet@gmail.com> wrote:
>
>>
>> > To disable gso you would have to use :
>> >
>> > ethtool -K wlan1 gso off
>>
>> Oh, thanks! This works. However I can't turn it on:
>>
>> ; ethtool -K wlan1 gso on
>> Could not change any device features
>>
>> ..so I guess it makes no sense to re-run tests because:
>>
>> ; ethtool -k wlan1 | grep generic
>>         tx-checksum-ip-generic: on [fixed]
>> generic-segmentation-offload: off [requested on]
>> generic-receive-offload: on
>>
>> And this seems to never change.
>
> GSO requires SG (Scatter Gather)
>
> Are you sure this hardware has no SG support ?

The hardware itself seems to be capable. The firmware is a problem
though. I'm also not sure if mac80211 can handle this as is. No 802.11
driver seems to support SG except wil6210 which uses cfg80211 and
netdevs directly.


Michał