Messages in this thread | | | Date | Tue, 21 Jan 2020 11:04:54 +0100 (CET) | Subject | Re: [PATCH V2,net-next, 1/2] hv_netvsc: Add XDP support | From | David Miller <> |
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From: Haiyang Zhang <haiyangz@microsoft.com> Date: Mon, 20 Jan 2020 14:22:36 -0800
> +u32 netvsc_run_xdp(struct net_device *ndev, struct netvsc_channel *nvchan, > + struct xdp_buff *xdp) > +{ > + struct page *page = NULL; > + void *data = nvchan->rsc.data[0]; > + u32 len = nvchan->rsc.len[0]; > + struct bpf_prog *prog; > + u32 act = XDP_PASS;
Please use reverse christmas tree ordering of local variables.
> + xdp->data_hard_start = page_address(page); > + xdp->data = xdp->data_hard_start + NETVSC_XDP_HDRM; > + xdp_set_data_meta_invalid(xdp); > + xdp->data_end = xdp->data + len; > + xdp->rxq = &nvchan->xdp_rxq; > + xdp->handle = 0; > + > + memcpy(xdp->data, data, len);
Why can't the program run directly on nvchan->rsc.data[0]?
This data copy defeats the whole performance gain of using XDP.
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