Hello, I'm currently working on OpenVswitch. Yours goals are to use it like a big virtual switchs for hundreds of VM.
Fonctionnally it's perferk, works great. Nice peace of works ! :) But I've got some performance issue, and I have some questions about that ;) Well I use RHEL6/KVM and openvswitch 1.0.3. There is a central server with openVswitch and many openVswitch connected to it with GRE tunnel. I've run many tests and the results are quite interesting : 1/In standalone mode (ie VMs on the same hypervisor) : ======================================================================================== Globally I have a throught put of 80% of the main network cards : - with a 10Gbit card, I've got 8Gbit max bandwitch - with a 1Gbit card, I've got 800Mbit max nadwitch I've run many tests (kernel optimisation, less or more VMs ,etc...) and the results is pretty identical : ~80% of main network card. Well, that's not bad at all, but is there a hard limitation in the code of openvswitch ? an auto-probe of max bandwith ? In the documentation I've found about qos/max_rate : ------------------------------------------------------------------- Maximum rate shared by all queued traffic, in bit/s. Optional. If not specified, for physi- cal interfaces, the default is the link rate. For other interfaces or if the link rate cannot be determined, the default is currently 100 Mbp ------------------------------------------------------------------- OpenVswitch seems to use something call "ETHTOOL_GSET" when a port/interface is addeed. >From my investigation, it seems that this fonction interrogate the link speed of the device. Is there a king of relation ? But it's strange, because when i interrogate with ethtool a tap interface I've got : "Speed: 10Mb/s". I don't know how to change this parameter because ethtool can't do that :"Operation not supported" In pratice the VM throughput can go up than 10Mb so I'm suposed taht openvswitch doesn't care. 2/With GRE/CAPWAP tunnel : VMs accroos many hypervisors ======================================================================================== In this configuration VM throughput does'nt exceed about 100/120 Mbit/s. If I've run lots of VM, I can saturate the link (10Gbit), but I must run lot's of VM. I've done some tests with capwap tunnel, and the results are pretty the same. Is there a bandwitch limitation inside openvswitch when using a GRE/CAPWAP Tunnel ? Wall in fine If you need more details, ask them ;) Any help is welcome :) Regards, -- Benoit
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