Re: [PATCH netdev 0/5] virtio-net support xdp socket zero copy xmit

From: "Michael S. Tsirkin" <mst@redhat.com>
To: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Cc: netdev@vger.kernel.org, dust.li@linux.alibaba.com,
	tonylu@linux.alibaba.com, "Jason Wang" <jasowang@redhat.com>,
	"David S. Miller" <davem@davemloft.net>,
	"Jakub Kicinski" <kuba@kernel.org>,
	"Björn Töpel" <bjorn.topel@intel.com>,
	"Magnus Karlsson" <magnus.karlsson@intel.com>,
	"Jonathan Lemon" <jonathan.lemon@gmail.com>,
	"Alexei Starovoitov" <ast@kernel.org>,
	"Daniel Borkmann" <daniel@iogearbox.net>,
	"Jesper Dangaard Brouer" <hawk@kernel.org>,
	"John Fastabend" <john.fastabend@gmail.com>,
	"Andrii Nakryiko" <andrii@kernel.org>,
	"Martin KaFai Lau" <kafai@fb.com>,
	"Song Liu" <songliubraving@fb.com>, "Yonghong Song" <yhs@fb.com>,
	"KP Singh" <kpsingh@kernel.org>,
	"open list:VIRTIO CORE AND NET DRIVERS"
	<virtualization@lists.linux-foundation.org>,
	"open list" <linux-kernel@vger.kernel.org>,
	"open list:XDP SOCKETS (AF_XDP)" <bpf@vger.kernel.org>
Subject: Re: [PATCH netdev 0/5] virtio-net support xdp socket zero copy xmit
Date: Tue, 5 Jan 2021 07:25:11 -0500	[thread overview]
Message-ID: <20210105072316-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <cover.1609837120.git.xuanzhuo@linux.alibaba.com>

On Tue, Jan 05, 2021 at 05:11:38PM +0800, Xuan Zhuo wrote:
> The first patch made some adjustments to xsk.
> 
> The second patch itself can be used as an independent patch to solve the problem
> that XDP may fail to load when the number of queues is insufficient.
> 
> The third to last patch implements support for xsk in virtio-net.
> 
> A practical problem with virtio is that tx interrupts are not very reliable.
> There will always be some missing or delayed tx interrupts.

Would appreciate a bit more data on this one. Is this a host bug? Device bug?
Can we limit the work around somehow?

> So I specially added
> a point timer to solve this problem. Of course, considering performance issues,
> The timer only triggers when the ring of the network card is full.
> 
> Regarding the issue of virtio-net supporting xsk's zero copy rx, I am also
> developing it, but I found that the modification may be relatively large, so I
> consider this patch set to be separated from the code related to xsk zero copy
> rx.
> 
> Xuan Zhuo (5):
>   xsk: support get page for drv
>   virtio-net: support XDP_TX when not more queues
>   virtio-net, xsk: distinguish XDP_TX and XSK XMIT ctx
>   xsk, virtio-net: prepare for support xsk
>   virtio-net, xsk: virtio-net support xsk zero copy tx
> 
>  drivers/net/virtio_net.c    | 643 +++++++++++++++++++++++++++++++++++++++-----
>  include/linux/netdevice.h   |   1 +
>  include/net/xdp_sock_drv.h  |  10 +
>  include/net/xsk_buff_pool.h |   1 +
>  net/xdp/xsk_buff_pool.c     |  10 +-
>  5 files changed, 597 insertions(+), 68 deletions(-)
> 
> --
> 1.8.3.1