If that's useful, then it makes sense to me and I'd have no objection.
On Mon, Apr 24, 2017 at 10:06:17AM +0000, O Mahony, Billy wrote: > Hi Ben, Darrell, > > I've done some PoC work on this kind of traffic prioritization. However with > OVS-DPDK's run-to-completion model the issue I find the same issue as you > outlined - by the time the priority of the packet has been determined most of > the effort to process the packet has already been spent. > > So, I relied on using hardware offload i.e. FlowDirector on the NIC to > analyse and allocate packets to high and low priority queues and then > modifying the PMD (dpif_netdev_run ) to read preferentially from the high > priority queue. The results were good for overload situations - packets on > the priority queue not dropped. In terms of latency there was an improvement > but there was still a long tail to the latency profile. i..e The latency > profile moved down but not left. > > As Darrell pointed out for egress scheduling, perhaps this kind of ingress > prioritization can be encapsulated as an optional property of a port? > > If the port can implement the prioritization (either by offloading to > hardware or in software) it can accept the property being set; If not it can > return ENOTSUPP? > > There is currently HWOL use-cases being gathered for OVS-DPDK: > https://docs.google.com/document/d/1A8adu1xzg53bzcFKINhffYyC0nCQjqwqnI1jAFx2sck/edit?usp=sharing > + Kevin who is co-ordinating that. > > Thanks, > Billy. > > > > -----Original Message----- > > From: Ben Pfaff [mailto:b...@ovn.org] > > Sent: Friday, April 21, 2017 10:39 PM > > To: O Mahony, Billy <billy.o.mah...@intel.com> > > Cc: ovs-discuss@openvswitch.org; Darrell Ball <db...@vmware.com> > > Subject: Re: [ovs-discuss] prioritizing latency-sensitive traffic > > > > Thanks for letting us know. I'm happy to continue the conversation if there > > are interesting ideas; it's a frustrating situation, frankly, and I'd love > > to hear > > creative approaches. > > > > On Tue, Apr 18, 2017 at 10:01:28AM +0000, O Mahony, Billy wrote: > > > Hi Ben, Darrell, > > > > > > It sounds like the general feeling is that any kind of tc pre-processing > > > is not > > worth it and the existing egress queing/QoS facilities should suffice. > > > > > > Thanks for your comments. > > > > > > /Billy > > > > > > > > > > > > > -----Original Message----- > > > > From: Ben Pfaff [mailto:b...@ovn.org] > > > > Sent: Thursday, April 13, 2017 7:47 PM > > > > To: O Mahony, Billy <billy.o.mah...@intel.com> > > > > Cc: ovs-discuss@openvswitch.org > > > > Subject: Re: [ovs-discuss] prioritizing latency-sensitive traffic > > > > > > > > I don't know how much more OVS can contribute to this than it already > > does. > > > > By the time that OVS has classified a packet to the extent that is > > > > necessary to determine that it should be handled with a high > > > > priority, OVS has already done most of the work that it does on a > > > > packet. > > > [[BO'M]] I'm investigating how I could go about classifying packets > > > before the main The work to transmit the > > > > packet is not part of OVS's job, it is the job of the driver, and at > > > > most OVS can mark the packet with a priority or a queue. OVS can > > > > already do that. So the usual answer is that it's a matter of > > > > configuring QoS in the driver to do what the user wants. > > > > > > > > On Mon, Apr 10, 2017 at 09:30:12AM +0000, O Mahony, Billy wrote: > > > > > Hi Everybody, > > > > > > > > > > I just wanted to reflag this discussion below about possible > > > > > methods of > > > > how to prioritize certain types of traffic handled by OVS. > > > > > > > > > > By prioritize I mean either or both of: > > > > > a) 'priority' packets are sent to their destination port faster > > > > > than other packets > > > > > b) in an overloaded situation the switch drops non-prioritized > > > > > packets > > > > rather than prioritized packets. > > > > > > > > > > Also just to be clear I am discussing kernel ovs here. Also I'm > > > > > looking at > > > > doing this without writing new code - ie is it possible and if so > > > > how is it configured using existing OVS. > > > > > > > > > > Thanks again, > > > > > Billy. > > > > > > > > > > > -----Original Message----- > > > > > > From: ovs-discuss-boun...@openvswitch.org [mailto:ovs-discuss- > > > > > > boun...@openvswitch.org] On Behalf Of O Mahony, Billy > > > > > > Sent: Friday, November 25, 2016 5:04 PM > > > > > > To: ovs-discuss@openvswitch.org > > > > > > Subject: [ovs-discuss] prioritizing latency-sensitive traffic > > > > > > > > > > > > Hi, > > > > > > > > > > > > I have been performing tests investigating latency profiles of > > > > > > low-bandwidth time-sensitive traffic when the system is busy > > > > > > with > > > > 'normal' traffic. > > > > > > Unsurprisingly the latency-sensitive traffic is affected by the > > > > > > normal traffic and has basically the same latency profile as the > > > > > > normal > > > > traffic. > > > > > > > > > > > > I would like to be able to perform prioritization of traffic as > > > > > > some protocols such as PTP would benefit greatly from having > > > > > > it's packets 'jump > > > > the queue'. > > > > > > > > > > > > From skimming the documentation it looks that ingress QoS offers > > > > > > only policing (rate-limiting). Is this actually the case or > > > > > > maybe I'm not looking in the right place? > > > > > > > > > > > > But if so, I am looking at some alternatives: > > > > > > > > > > > > a) create two separate egress ports and have PTP listen on one > > > > > > port, everything else listen on the other port and use normal > > > > > > forwarding rules to send PTP traffic incoming from eth0 to it's > > > > > > own port. Something > > > > like: > > > > > > > > > > > > other apps ptp_daemon > > > > > > + + > > > > > > + + > > > > > > if_norm if_ptp > > > > > > + + > > > > > > | | > > > > > > | | > > > > > > ++------------++ > > > > > > | | > > > > > > | ovs | > > > > > > | | > > > > > > +-----+--------+ > > > > > > | > > > > > > + > > > > > > eth0 > > > > > > > > > > > > b) create prioritized queues on a port and use match and actions > > > > > > such as > > > > > > set_queue(queue) and enqueue(port, queue) on ingress traffic to > > > > > > forward the PTP traffic to the higher priority queue. However I > > > > > > think queue priority for this case only relates to which queue > > > > > > get to consume the bandwidth of the port first and not about > > > > > > changing the order in which the packets egress the port. > > > > > > > > > > > > c) Or perhaps I can re-use tc PRIO or CBQ qdiscs by passing all > > > > > > traffic to tc first before ovs? > > > > > > > > > > > > other apps > > > > > > | > > > > > > | > > > > > > if_norm > > > > > > + > > > > > > | > > > > > > | > > > > > > +--------------+ > > > > > > | | > > > > > > | ovs | > > > > > > | | > > > > > > +-----+--------+ > > > > > > | > > > > > > | > > > > > > tc ----- if_ptp ---- ptp_daemon > > > > > > + > > > > > > eth0 > > > > > > > > > > > > Any thoughts, ideas or clarifications most welcome. > > > > > > > > > > > > Thanks, > > > > > > Billy. > > > > > > > > > > > > _______________________________________________ > > > > > > discuss mailing list > > > > > > disc...@openvswitch.org > > > > > > https://mail.openvswitch.org/mailman/listinfo/ovs-discuss > > > > > _______________________________________________ > > > > > discuss mailing list > > > > > disc...@openvswitch.org > > > > > https://mail.openvswitch.org/mailman/listinfo/ovs-discuss _______________________________________________ discuss mailing list disc...@openvswitch.org https://mail.openvswitch.org/mailman/listinfo/ovs-discuss