On 09/07/2016 10:58 PM, Saeed Mahameed wrote:
On Fri, Jul 8, 2016 at 5:15 AM, Brenden Blanco <bbla...@plumgrid.com> wrote:
+ /* A bpf program gets first chance to drop the packet. It may
+ * read bytes but not past the end of the frag.
+ */
+ if (prog) {
+ struct xdp_buff xdp;
+ dma_addr_t dma;
+ u32 act;
+
+ dma = be64_to_cpu(rx_desc->data[0].addr);
+ dma_sync_single_for_cpu(priv->ddev, dma,
+ priv->frag_info[0].frag_size,
+ DMA_FROM_DEVICE);
In case of XDP_PASS we will dma_sync again in the normal path, this
can be improved by doing the dma_sync as soon as we can and once and
for all, regardless of the path the packet is going to take
(XDP_DROP/mlx4_en_complete_rx_desc/mlx4_en_rx_skb).
I agree with Saeed, dma_sync is a heavy operation that is now done twice
for all packets with XDP_PASS.
We should try our best to avoid performance degradation in the flow of
unfiltered packets.
Regards,
Tariq
