netdev - Re: Peak TCP performance

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Date:	Fri, 11 Oct 2013 00:21:36 -0400
From:	Kyle Hubert <khubert@...il.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	netdev@...r.kernel.org
Subject: Re: Peak TCP performance

On Thu, Oct 10, 2013 at 11:44 PM, Eric Dumazet <eric.dumazet@...il.com> wrote:
>> Also, my copy of ethtool does not recognize tx-nocache-copy. However,
>> I do have control over the net device. Is there something there I can
>> set, or is tx-nocache-copy also a new feature? I'll start digging.
>>
>
> nocache-copy was added in 3.0, but I do find its not a gain for current
> cpus.
>
> You could get a fresh copy of ethtool sources :
>
> git clone git://git.kernel.org/pub/scm/network/ethtool/ethtool.git
> cd ethtool
> ./autogen.sh  ...

That did the trick. Thanks for the help! Is there somewhere I can read
up on this feature? A lot of the netdev features are opaque to me.
Also, I can set NETIF_F_NOCACHE_COPY in the netdev->features to set
this by default, yes?

This at least mirrors the performance improvement that I see when
forwarding, however I still see reserved CPU time. Is there a way to
push it even farther?

-Kyle
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