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Message-ID: <65e2212e66769_158220294f@willemb.c.googlers.com.notmuch>
Date: Fri, 01 Mar 2024 13:40:46 -0500
From: Willem de Bruijn <willemdebruijn.kernel@...il.com>
To: Maciej Fijalkowski <maciej.fijalkowski@...el.com>,
Yunjian Wang <wangyunjian@...wei.com>
Cc: mst@...hat.com,
willemdebruijn.kernel@...il.com,
jasowang@...hat.com,
kuba@...nel.org,
bjorn@...nel.org,
magnus.karlsson@...el.com,
jonathan.lemon@...il.com,
davem@...emloft.net,
bpf@...r.kernel.org,
netdev@...r.kernel.org,
linux-kernel@...r.kernel.org,
kvm@...r.kernel.org,
virtualization@...ts.linux.dev,
xudingke@...wei.com,
liwei395@...wei.com
Subject: Re: [PATCH net-next v2 3/3] tun: AF_XDP Tx zero-copy support
Maciej Fijalkowski wrote:
> On Wed, Feb 28, 2024 at 07:05:56PM +0800, Yunjian Wang wrote:
> > This patch set allows TUN to support the AF_XDP Tx zero-copy feature,
> > which can significantly reduce CPU utilization for XDP programs.
>
> Why no Rx ZC support though? What will happen if I try rxdrop xdpsock
> against tun with this patch? You clearly allow for that.
This is AF_XDP receive zerocopy, right?
The naming is always confusing with tun, but even though from a tun
PoV this happens on ndo_start_xmit, it is the AF_XDP equivalent to
tun_put_user.
So the implementation is more like other device's Rx ZC.
I would have preferred that name, but I think Jason asked for this
and given tun's weird status, there is something bo said for either.
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