Subject: Re: [PATCH RFC] tun: experimental zero copy tx support
From: Shirley Ma <mashirle@us.ibm.com>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: "David S. Miller" <davem@davemloft.net>,
        Stephen Hemminger <shemminger@vyatta.com>,
        Joe Perches <joe@perches.com>, Jason Wang <jasowang@redhat.com>,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        Ian.Campbell@citrix.com, kvm@vger.kernel.org
In-Reply-To: <20120513155206.GA26847@redhat.com>
References: <20120513155206.GA26847@redhat.com>
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Date: Mon, 14 May 2012 10:34:50 -0700
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On Sun, 2012-05-13 at 18:52 +0300, Michael S. Tsirkin wrote:
> Let vhost-net utilize zero copy tx when the experimental
> zero copy mode is enabled and when used with tun.  This works on
> top of the patchset 'copy aside frags with destructors' that I posted
> previously. This is not using tcp so doesn't have the
> issue with early skb cloning noticed by Ian.
> 
> For those that wish to test this with kvm, I intend to post a patchset
> +
> git tree with just the necessary bits from the destructor patch
> a bit later.
> 
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> 

Hello Mike,

Have you tested this patch? I think the difference between macvtap and
tap is tap forwarding the packet to bridge. The zerocopy is disabled in
this case.

Shirley

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