Hi, Currently every DPDK mbuf in OVS has the `refcnt` set to one. Output to multiple ports is handled by making a copy of the packet's payload (see `may_steal` in dp_netdev_execute_actions(), and in netdev_send()).
You're right, having a `refcnt` != 1 might be necessary to use rte_ipv4_fragment_packet() or to support certain offloading capabilities (currently not implemented in OVS). Does this answer you question? Daniele On 15/10/2015 12:41, "Ben Pfaff" <b...@nicira.com> wrote: >I don't understand what you're asking for. > >Daniele or Pravin, I think that you know the DPDK datapath well. Do you >understand what David wants or why? > >On Thu, Oct 15, 2015 at 01:15:11PM -0500, David Evans wrote: >> Thanks Ben, >> >> If that¹s the case, then it would be better to be adding custom action >>that applies prior to this group action, to update the refcnt. >> >> I expect it just has to happen some time before the first PMD has >>finished processing the packet so that the packet does not get deleted >>by the tx routine before other PMD¹s have seen the packet. >> >> Cheers >> Dave. >> >> >> >> > On Oct 12, 2015, at 12:23 PM, Ben Pfaff <b...@nicira.com> wrote: >> > >> > Your change isn't going to have much effect because most packets don't >> > go through the translation process. If you try to force all packets >> > through translation, it will kill performance. >> > >> > I think that you should read this paper that describes the various >> > caching layers in Open vSwitch: >> > >>https://urldefense.proofpoint.com/v2/url?u=http-3A__openvswitch.org_suppo >>rt_papers_nsdi2015.pdf&d=BQIDaQ&c=Sqcl0Ez6M0X8aeM67LKIiDJAXVeAw-YihVMNtXt >>-uEs&r=SmB5nZacmXNq0gKCC1s_Cw5yUNjxgD4v5kJqZ2uWLlE&m=xaCdqbPumJKYqzipA2A5 >>CYRDmbv1Q_lFRe2Aw2_bqpQ&s=GdugumekoH_nwJ4XnY2ip92yy-YoGNIV8Rj_tQkQ_b0&e= >> > >> > On Mon, Oct 12, 2015 at 11:56:03AM -0500, David Evans wrote: >> >> Hi Ben, >> >> >> >> When i use the OFPGT11_ALL group action, the packets for a flow >>will be sent out all buckets in a group. (in my case all the buckets are >>ports to transmit out) >> >> >> >> I added a group_bucket_count to the context >> >> and >> >> in xlate_all_group fn the following. >> >> >> >> group_dpif_get_buckets(group, &buckets); >> >> + if(ctx->group_bucket_count == 0){ >> >> + LIST_FOR_EACH (bucket, list_node, buckets) { >> >> + ctx->group_bucket_count++; >> >> + } >> >> + } >> >> + if(ctx->xin->packet) >> >> + if(ctx->xin->packet->source == DPBUF_DPDK) >> >> + >> >> rte_pktmbuf_refcnt_update(&ctx->xin->packet->mbuf,ctx->group_bucket_cou >>nt); >> >> LIST_FOR_EACH (bucket, list_node, buckets) { >> >> >> >> this stops the transmit pmd¹s attempting to free the packet until >>all the buckets( ports ) have transmitted it. >> >> My switch also does reassembly on rx - this refcnt is necessary for >>handling multi-segment dpdk buffers too. >> >> I also changed the segment free to rte_pktmbuf_free in netdev-dpdk.c >>for this purpose. >> >> I¹m expecting it will also be important for tso or the possibility >>of using rte_ipv4_fragment_packet on an outgoing port. >> >> >> >> i have between 6 and 12 PMD¹s depending on the number of dpdk ports >>running at any time, and if i use OFPGT11_ALL with many output >>buckets(ports) buffers will disappear from under some pmd¹s and cause >>segfaults etc.. >> >> >> >> Cheers, >> >> >> >> Dave. >> >> >> >>> On Oct 12, 2015, at 11:38 AM, Ben Pfaff <b...@nicira.com> wrote: >> >>> >> >>> On Wed, Oct 07, 2015 at 05:36:18PM -0500, David Evans wrote: >> >>>> While using netdev-dpdk - When i add a rule for which the action >>is to >> >>>> send to a group (type=all) containing (x) output buckets (ports) >>how >> >>>> can i increment the dp_packet->pkt_mbuf¹s refcnt to (x) so that the >> >>>> packet is not deleted before it has transmitted all ports(buckets) >>in >> >>>> the group. >> >>>> >> >>>> Perhaps in ofproto-dpif-xlate.c function xlate_all_group find the >> >>>> packet and apply the ctx->xin->packet->mbuf->refcnt ? Will that >>work >> >>>> for all packets for a ctx? >> >>> >> >>> I don't understand what relationship you expect here. A group has >>no >> >>> direct relationship to a packet. Translation produces a flat list >>of >> >>> simple actions that don't refer back to the group. >> >> >> _______________________________________________ discuss mailing list discuss@openvswitch.org http://openvswitch.org/mailman/listinfo/discuss
