From: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>
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.
