From 7358877ac11041a22ce1cb35c352809051eac48f Mon Sep 17 00:00:00 2001 From: Jesper Dangaard Brouer Date: Thu, 14 May 2020 12:49:58 +0200 Subject: hv_netvsc: Add XDP frame size to driver The hyperv NIC driver does memory allocation and copy even without XDP. In XDP mode it will allocate a new page for each packet and copy over the payload, before invoking the XDP BPF-prog. The positive thing it that its easy to determine the xdp.frame_sz. The XDP implementation for hv_netvsc transparently passes xdp_prog to the associated VF NIC. Many of the Azure VMs are using SRIOV, so majority of the data are actually processed directly on the VF driver's XDP path. So the overhead of the synthetic data path (hv_netvsc) is minimal. Then XDP is enabled on this driver, XDP_PASS and XDP_TX will create the SKB via build_skb (based on the newly allocated page). Now using XDP frame_sz this will provide more skb_tailroom, which netstack can use for SKB coalescing (e.g tcp_try_coalesce -> skb_try_coalesce). V3: Adjust patch desc to be more positive. Signed-off-by: Jesper Dangaard Brouer Signed-off-by: Alexei Starovoitov Cc: Wei Liu Cc: "K. Y. Srinivasan" Cc: Haiyang Zhang Cc: Stephen Hemminger Link: https://lore.kernel.org/bpf/158945339857.97035.10212138582505736163.stgit@firesoul --- drivers/net/hyperv/netvsc_drv.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/net/hyperv/netvsc_drv.c') diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c index 5de57fc3ec60..6267f706e8ee 100644 --- a/drivers/net/hyperv/netvsc_drv.c +++ b/drivers/net/hyperv/netvsc_drv.c @@ -795,7 +795,7 @@ static struct sk_buff *netvsc_alloc_recv_skb(struct net_device *net, if (xbuf) { unsigned int hdroom = xdp->data - xdp->data_hard_start; unsigned int xlen = xdp->data_end - xdp->data; - unsigned int frag_size = netvsc_xdp_fraglen(hdroom + xlen); + unsigned int frag_size = xdp->frame_sz; skb = build_skb(xbuf, frag_size); -- cgit v1.2.3