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Date: Mon, 30 Jan 2017 18:53:05 -0800 From: Alexei Starovoitov <ast@...com> To: John Fastabend <john.fastabend@...il.com>, <bjorn.topel@...il.com>, <jasowang@...hat.com>, <alexander.duyck@...il.com>, <brouer@...hat.com> CC: <john.r.fastabend@...el.com>, <netdev@...r.kernel.org> Subject: Re: [RFC PATCH 2/2] ixgbe: add af_packet direct copy support On 1/27/17 1:34 PM, John Fastabend wrote: > + h2 = page_address(rx_buffer->page) + rx_buffer->page_offset - hdrlen; > + eth = page_address(rx_buffer->page) + rx_buffer->page_offset, I don't think it compiles ;) > + /* This indicates a bug in ixgbe leaving for testing purposes */ > + WARN_ON(TP_STATUS_USER & h2->tp_status); > + len = le16_to_cpu(rx_desc->wb.upper.length); > + h2->tp_len = len; > + h2->tp_snaplen = len; > + h2->tp_mac = ALIGN(TPACKET_ALIGN(TPACKET2_HDRLEN), L1_CACHE_BYTES); > + h2->tp_net = h2->tp_mac + ETH_HLEN; > + h2->tp_sec = div_s64_rem(ns, NSEC_PER_SEC, &rem); > + h2->tp_nsec = rem; > + > + sll = (void *)h2 + TPACKET_ALIGN(sizeof(struct tpacket2_hdr)); > + sll->sll_halen = ETH_HLEN; > + memcpy(sll->sll_addr, eth->h_source, ETH_ALEN); > + sll->sll_family = AF_PACKET; > + sll->sll_hatype = rx_ring->netdev->type; > + sll->sll_protocol = eth->h_proto; > + sll->sll_pkttype = PACKET_HOST; > + sll->sll_ifindex = rx_ring->netdev->ifindex; performance wise it looks very expensive to do all these header copies and integer divide for every packet. I think unless we move to new dumb and simple header format performance of this approach is not going to be satisfactory.
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