Hello, What MTU have You got configured on VMs? I had issue with performance on vxlan network with standard MTU (1500) but when I configured Jumbo frames on vms and on hosts then it was much better.
-- Best regards / Pozdrawiam Sławek Kapłoński [email protected] On Fri, 15 Apr 2016, Rick Jones wrote: > On 04/14/2016 07:10 PM, Kenny Ji-work wrote: > >Hi all, > > > >In the environment of openstack kilo, I test the bandwidth in the scene > >which VxLan being used. The result show that the vxlan can only support > >up to 1 gbits bandwidth. Is this a bug or any else issue, or is there > >some hotfix to solve the issue? Thank you for answering! > > I'm glossing over some details, but broadly speaking, a single network flow > cannot take advantage of more than one CPU in a system. And while network > speeds have been continuing to increase, per-core speeds haven't really gone > up much over the last five to ten years. > > So, to get "speed/link rate" networking stacks have become dependent on > stateless offloads - Checksum Offload (CKO) TCP Segmentation Offload > (TSO/GSO) and Generic Receive Offload 9GRO). And until somewhat recently, > NICs did not offer stateless offloads for VxLAN-encapsulated traffic. So, > one effectively has a "dumb" NIC without stateless offloads. And depending > on what sort of processor you have, that limit could be down around 1 > Gbit/s. Only some of the more recent 10GbE NICs offer stateless offload of > VxLAN-encapsulated traffic, and similarly their more recent drivers and > networking stacks. > > In olden days, before the advent of stateless offloads there was a rule of > thumb - 1 Mbit/s per MHz. That was with "pure" bare-iron networking - no > VMs, no encapsulation. Even then it was a bit hand-wavy, and may have > originated in the land of SPARC processors. But hopefully it conveys the > idea of what it means to lose the stateless offloads. > > So, it would be good to know what sort of CPUs are involved (down to the > model names and frequencies) as well as the NICs involved - again, full > naming, not just the brand name. > > And it is just a paranoid question, but is there any 1 Gbit/s networking in > your setup at all? > > happy benchmarking, > > rick jones > > > __________________________________________________________________________ > OpenStack Development Mailing List (not for usage questions) > Unsubscribe: [email protected]?subject:unsubscribe > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
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