Re: [RFC PATCH net-next V2 6/6] virtio-net: support XDP rx handler
From: Jesper Dangaard Brouer <hidden>
Date: 2018-08-14 09:22:31
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On Mon, 13 Aug 2018 11:17:30 +0800 Jason Wang [off-list ref] wrote:
This patch tries to add the support of XDP rx handler to virtio-net. This is straight-forward, just call xdp_do_pass() and behave depends on its return value. Test was done by using XDP_DROP (xdp1) for macvlan on top of virtio-net. PPS of SKB mode was ~1.2Mpps while PPS of native XDP mode was ~2.2Mpps. About 83% improvement was measured.
I'm not convinced... Why are you not using XDP_REDIRECT, which is already implemented in receive_mergeable (which you modify below). The macvlan driver just need to implement ndo_xdp_xmit(), and then you can redirect (with XDP prog from physical driver into the guest). It should be much faster...
quoted hunk ↗ jump to hunk
Notes: for RFC, only mergeable buffer case was implemented. Signed-off-by: Jason Wang <redacted> --- drivers/net/virtio_net.c | 11 +++++++++++ 1 file changed, 11 insertions(+)diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 62311dd..1e22ad9 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c@@ -777,6 +777,7 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, rcu_read_lock(); xdp_prog = rcu_dereference(rq->xdp_prog); if (xdp_prog) { + rx_xdp_handler_result_t ret; struct xdp_frame *xdpf; struct page *xdp_page; struct xdp_buff xdp;@@ -825,6 +826,15 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, switch (act) { case XDP_PASS: + ret = xdp_do_pass(&xdp); + if (ret == RX_XDP_HANDLER_DROP) + goto drop; + if (ret != RX_XDP_HANDLER_FALLBACK) { + if (unlikely(xdp_page != page)) + put_page(page); + rcu_read_unlock(); + goto xdp_xmit; + } /* recalculate offset to account for any header * adjustments. Note other cases do not build an * skb and avoid using offset@@ -881,6 +891,7 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, case XDP_ABORTED: trace_xdp_exception(vi->dev, xdp_prog, act); /* fall through */ +drop: case XDP_DROP: if (unlikely(xdp_page != page)) __free_pages(xdp_page, 0);
-- Best regards, Jesper Dangaard Brouer MSc.CS, Principal Kernel Engineer at Red Hat LinkedIn: http://www.linkedin.com/in/brouer