From: Jesper Dangaard Brouer <brouer@redhat.com>
To: Jason Wang <jasowang@redhat.com>
Cc: mst@redhat.com, netdev@vger.kernel.org, john.fastabend@gmail.com,
linux-kernel@vger.kernel.org,
virtualization@lists.linux-foundation.org, brouer@redhat.com
Subject: Re: [PATCH net-next 0/2] virtio-net: re enable XDP_REDIRECT for mergeable buffer
Date: Thu, 1 Mar 2018 10:10:38 +0100 [thread overview]
Message-ID: <20180301101038.4253424d@redhat.com> (raw)
In-Reply-To: <1519874345-10235-1-git-send-email-jasowang@redhat.com>
On Thu, 1 Mar 2018 11:19:03 +0800
Jason Wang <jasowang@redhat.com> wrote:
> This series tries to re-enable XDP_REDIRECT for mergeable buffer which
> was removed since commit 7324f5399b06 ("virtio_net: disable
> XDP_REDIRECT in receive_mergeable() case"). Main concerns are:
>
> - not enough tailroom was reserved which breaks cpumap
To address this at a more fundamental level, I would suggest that we/you
instead extend XDP to know it's buffers "frame" size/end. (The
assumption use to be, xdp_buff->data_hard_start + PAGE_SIZE, but
ixgbe+virtio_net broke that assumption).
It should actually be fairly easy to implement:
* Simply extend xdp_buff with a "data_hard_end" pointer.
Now cpumap is more safe... instead of crashing, it can now know/see when
it is safe to create an SKB using build_skb (could fallback to
dev_alloc_skb).
--
Best regards,
Jesper Dangaard Brouer
MSc.CS, Principal Kernel Engineer at Red Hat
LinkedIn: http://www.linkedin.com/in/brouer
WARNING: multiple messages have this Message-ID (diff)
From: Jesper Dangaard Brouer <brouer@redhat.com>
To: Jason Wang <jasowang@redhat.com>
Cc: mst@redhat.com, virtualization@lists.linux-foundation.org,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
john.fastabend@gmail.com, brouer@redhat.com
Subject: Re: [PATCH net-next 0/2] virtio-net: re enable XDP_REDIRECT for mergeable buffer
Date: Thu, 1 Mar 2018 10:10:38 +0100 [thread overview]
Message-ID: <20180301101038.4253424d@redhat.com> (raw)
In-Reply-To: <1519874345-10235-1-git-send-email-jasowang@redhat.com>
On Thu, 1 Mar 2018 11:19:03 +0800
Jason Wang <jasowang@redhat.com> wrote:
> This series tries to re-enable XDP_REDIRECT for mergeable buffer which
> was removed since commit 7324f5399b06 ("virtio_net: disable
> XDP_REDIRECT in receive_mergeable() case"). Main concerns are:
>
> - not enough tailroom was reserved which breaks cpumap
To address this at a more fundamental level, I would suggest that we/you
instead extend XDP to know it's buffers "frame" size/end. (The
assumption use to be, xdp_buff->data_hard_start + PAGE_SIZE, but
ixgbe+virtio_net broke that assumption).
It should actually be fairly easy to implement:
* Simply extend xdp_buff with a "data_hard_end" pointer.
Now cpumap is more safe... instead of crashing, it can now know/see when
it is safe to create an SKB using build_skb (could fallback to
dev_alloc_skb).
--
Best regards,
Jesper Dangaard Brouer
MSc.CS, Principal Kernel Engineer at Red Hat
LinkedIn: http://www.linkedin.com/in/brouer
next prev parent reply other threads:[~2018-03-01 9:10 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-01 3:19 [PATCH net-next 0/2] virtio-net: re enable XDP_REDIRECT for mergeable buffer Jason Wang
2018-03-01 3:19 ` Jason Wang
2018-03-01 3:19 ` [PATCH net-next 1/2] " Jason Wang
2018-03-01 8:41 ` Jesper Dangaard Brouer
2018-03-01 8:41 ` Jesper Dangaard Brouer
2018-03-01 9:11 ` Jason Wang
2018-03-01 9:11 ` Jason Wang
2018-03-01 13:36 ` Michael S. Tsirkin
2018-03-01 13:36 ` Michael S. Tsirkin
2018-03-02 4:20 ` Jason Wang
2018-03-02 4:20 ` Jason Wang
2018-03-01 3:19 ` Jason Wang
2018-03-01 3:19 ` [PATCH net-next 2/2] virtio-net: simplify XDP handling in small buffer Jason Wang
2018-03-01 3:19 ` Jason Wang
2018-03-01 8:02 ` Jesper Dangaard Brouer
2018-03-01 8:49 ` Jason Wang
2018-03-01 8:49 ` Jason Wang
2018-03-01 9:15 ` Jesper Dangaard Brouer
2018-03-01 9:15 ` Jesper Dangaard Brouer
2018-03-01 9:24 ` Jason Wang
2018-03-01 9:24 ` Jason Wang
2018-03-01 8:02 ` Jesper Dangaard Brouer
2018-03-01 9:10 ` Jesper Dangaard Brouer [this message]
2018-03-01 9:10 ` [PATCH net-next 0/2] virtio-net: re enable XDP_REDIRECT for mergeable buffer Jesper Dangaard Brouer
2018-03-01 9:23 ` Jason Wang
2018-03-01 10:35 ` Jesper Dangaard Brouer
2018-03-01 10:35 ` Jesper Dangaard Brouer
2018-03-01 13:15 ` Jason Wang
2018-03-01 13:15 ` Jason Wang
2018-03-01 14:16 ` Jesper Dangaard Brouer
2018-03-01 14:16 ` Jesper Dangaard Brouer
2018-03-02 4:17 ` Jason Wang
2018-03-02 4:17 ` Jason Wang
2018-03-01 13:40 ` Michael S. Tsirkin
2018-03-01 13:40 ` Michael S. Tsirkin
2018-03-01 9:23 ` Jason Wang
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